I'm sure this has been done but I can't find a thread, sorry if so!

I was wondering if a bigger baby means a more dificult labour. My daughter was 9lb (4kg 110gms) and 55cm and my labour was very difficult. I had an epidural, which stopped the contractions, but I was still in a huge amount of pain as she was decending. I haven't had another mother tell me they experienced this after an epidural. I'm sure some of it has to do with the strength of the epi, and for my top-up they gave me some sort of narcotic instead of the usual fluid they use. Could that have had something to do with it?