I had the epi, but definitely felt the urge to push when the time came so maybe it had worn down/off.
I remember the intial pain of crowning, but to be honest it was what spurned me on, and was the most amazing feeling that my child was coming.
Whatever works for you is exactly what you should do.
I held out for the epi, and this time, I will request it when I feel the need.
Everyone's experience is personal to them and I admire anyone who does it drug free, but at the same time, I think if you feel you need pain relief then thats exactly the right thing to do.