50minutes is completely normal for your first baby, the first is usually the longest to push out. Most hospitals consider 2hours of second stage to be normal for a first time mum as long as there is some signs of progress.

as for not feeling an urge, some people just don't for some reason, my friend never did and ended up having a 3hours second stage with a vacuum, we think it was something to do with the babies head position.

It's really nothing to feel guilty about, you may never have felt any stronger urge than pressure, everyone is different. I'm sure the midwives would have checked you were fully dilated so whether you pushed before a strong urge hasn't really affected the outcome ( except to make you feel bad unnecessarily! )