As a project manager, your job is not to tell developers how long they will take to finish a task.
Your job is to document the progress, communicate the timeline and progress to stakeholders and be clear about whether you are still on time.
I work with a lot of project managers that never wrote a line of code.
How do they estimate? They ask developers that are working on the topic and that is all to it, sometimes they get a second opinion from a more senior developer, if they feel they have.
I've tried to create docs to the best of my knowledge with goals, technologies to use, schemas, and such.
I am not sure exactly what kind of docs you are creating, but to me it sounds that you are doing more than what I would expect from a project manager.
E.g. architectural diagrams and technology decisions usually are not made by the project manager, but by an architect or lead developer or by whatever other developer who had time to do so.
The project managers job is to make sure there is adequate documentation, not to write all the documents by themselves.
Make sure you serve your different types of stakeholders:
a.) The developers rely on your plan, mostly to know what to do first and who to work on what. You really don't want to make to many decisions there, only the ones that need to be made or ones that have high impact.
E.g. you have a code freez1e for your iOS app approaching, this needs to be done first. You haven't made the final decision whether you change DB vendors? Do the DB integration later.
b.) Your customers are more interested in the results, and all they want to know is when you are done and what they will get. except when they want more features faster, which is often the case, and you will have to find a diplomatic answer ;)
c.) Other stakeholders might be teams that have to integrate with the code, other project managers that are waiting for your resources (people) to be free, legal, infrastructure services etc. they are usually interested in specific aspects of your project (e.g. compliance with GDPR, oh fun)
I do not see myself as one. The new developers are older and more experienced than me
You might feel a little bit of self-doubt, when you start thinking of your role as the captain of the football team.
If that happens, see yourself as the bus driver. You make sure the team finds their way into the stadium, so they don't have to worry about it and can focus on the game. But it is not necessary that you are an experienced player yourself.