This answer is a latecomer to an already rich conversation, but I feel it can really capture the situation and your feelings. I will try to make it brief and straight to the point and complement what has already been said.
- It's a delicate situation, but you will be fine
- You feel you haven't been completely honest
- Yes, you are a woman
- You want to talk your way out of the pressure
- Worst-case scenario
- How should you behave? Here are some tips
1. It is a delicate situation, but you will be fine
It is delicate, but solely in that if you do not act upon it, it will blow up. You will be fine, by harnessing this grace period in which you are expected to be overwhelmed. If you weren't, they wouldn't be doing anything special or truly relevant in the field or in the market.
You took a different approach to that hiring process. You made the decision to change; not just your job. Take the challenge and please allow yourself to enjoy it.
2. You feel you haven't been completely honest
Firstly, you have been selected from a set of top-level candidates. Imagine the CVs, technical skills, personalities, etc. they had to choose from, risk-free. You cannot be "just good at negotiation". And, since when? Since this last interview for which you "decided to negotiate harder"? To such extent as to scam your way into this position? The reality is that you are a top human being. The HR department and all the people that had to say a word concluded, all highly qualified, that your were the chosen one.
You may feel you have not been completely honest about your current level, but one never speaks only from our current self, but also from our future self. Maybe you not only "discarded it as a negotiation tactic", but also approached possible higher requirements by being honest and confident about your capabilities, which include leveling up professionally; as you have already, and as you would if the job required it. Well, it does; more than imagined, but you have the capability.
3. Yes, you are a woman
It is a reality that you are most likely to experience some situations. In such a competitive environment, people are going to test you, and talk about you, which we know is just natural. The higher the position, the more competitive and aggressive will be those surrounding it, which isn't bad. However, you should be ready for some comments and for possible coworkers trying to corner you, for reasons that are not here to be discussed, though interesting. Anyone denying this is out of touch with reality. It must be said though that it is most usually a game, that men are more into challenging each other, finding the most ingenious reply.
Make interactions with meticulous formality, establishing a highly respectful and professional environment. Avoid all informal scenarios until you feel confident enough with your technical abilities. Nourish the image others have about you by speaking little and being calm, because yes, a discrepancy can become a problem. Contrary to other answers, if you want to talk yourself down a bit, do so if it is humorous and portrays humility; it will be positively valued.
4. You want to talk your way out of the pressure
The solution to this distress won't come from being honest and confessing the truth about me. It seems like you are craving for a solution to the pressure that is upon you, placed by yourself and by the expectations. Firstly, remember that you have a grace period, that you are allowed to under-perform. Secondly, if you are impressed with some members of your team, canalize it by telling them, e.g., "stay healthy, you are one of the most valuable assets of our team". Find a coworker willing to dissect all the technicalities for you; you'd be surprised. Don't hesitate to ask anyone to share their knowledge with you, you might as well be evaluating them, and don't be too afraid to show that you are not the genius right there. Who knows what are the strengths, and how eminent, that brought you into this position; they don't know. You should be aware of your presence being also imposing. Be careful, however, with the questions you make and to whom.
It is OK how you are feeling; it is asking you for movement, because you cannot expect things to work out by just letting them happen (not at these levels of demand). Canalize your feelings into a plan to catch up with the project and the technology. As with an instrumentalist learning yet another musical instrument, you could be surprised to find all your current skills getting transferred and become exceptional. In your case, to the extent to "justify your higher level", or even to become a critical asset for the company. You are yet to know; give yourself time.
5. Worst-case scenario
It is often recommended for highly stressful endeavors to picture the worst-case scenario and solve it. Give yourself a generous but realistic time window and, if it is still that clear to you, communicate your intentions to abandon and switch companies. Definitely not the end of the world. It didn't work out, which is not that crucial to the company or to your career, both surely continuing to flourish.
It never feels right to quit, but it should when it is the best decision professionally (even the most legendary CEOs have a hard time stepping aside). If quitting really feels wrong, again: go ahead and tackle down this (beautiful) challenge.
6. How should you behave? Here are some tips
This may be in the end what you were asking for. Summing up:
- Be strict in being very formal in all your interactions. This is number one.
- Avoid undesired conversations by avoiding their most common scenarios, as well as their most common protagonists.
- If the time comes, do not hide and do not fake it; calmly find your way out without being delusive and while keeping a solid image. You can be humble, you can be humorous and, definitely, you can be relaxed about being overwhelmed in a new project (it is what is natural if you are not "underhired" but healthily ambitious).
- Don't talk about your feelings with strangers.
- Speak little. As I say, if you want to enhance your competence, act more like a cat than a dog.
- People will have confidence in you if you are calm and confident in yourself.
- Don't be afraid to show you are getting your head around the project and the technology because you need your coworkers to help you on this. Find those healthy minds willing to teach. Remember that you are a respected figure and seeking for knowledge will extend this view if done right.
- Making a compliment to a team member can alleviate the stress of having to be "clearly better" much more appropriately that confessing your "true technical level".
- If you want to be all this precise and accurate in procedure, make sure to have real fun out of work or you will be done soon.
- Find someone outside of work to talk to about this and about your progress. Maybe also a professional; you may know top executives do this.
- Speaking of mentoring, you may want to try to look for someone with the hard skills you are aiming at, maybe through LinkedIn,and pay for some consulting.
- Act with the feeling that you are an investment to the company which everyone should support and assist and that will eventually shine.