I received a job offer on 12th May. While I was pretty much 100% ready to accept, I decided to reply with a counteroffer as the offered salary was actually in the lower range for the position and there is only medical cover (no other benefits) and annual leave will be 10 days less than my current job. I was polite and respectful in my counteroffer and persuaded that I worth more and asked for the higher range salary. I think I was asking quite high but I stated that we can come to a mutual agreement.
I've never negotiated salary before, so this was very stressful for me. I was offered 56k and I countered with 66k and extra 3 days AL, expecting them to come back with a much lower number, which I'd almost definitely be fine with. On 18th May, the HR asked me to provide them the current salary with payment proof. On 19th May, I replied that salary is confidential due to Data Privacy. Since then, there is no reply. I am terrified that they'd simply revoke the offer instead of negotiating.
Of course, I understand that HR needs time, which has calmed me somewhat, but the fact that it's now 23rd May (three working days since I counteroffered) and I've still heard no response is freaking me out. I really want that job and would accept even if they are firm with the initial offer.
Should I e-mail back and what to say in the email? Should I restate my flexibility on the number? Should I say I would accept the initial offer? Should I give it one more day? (There is no deadline written.)