Trying to figure sex out. Help!

So, my boyfriend and I are both in university and have been dating for a year. I feel like this is a good situation and I feel very comfortable and ready to have sex. We are using condoms and lube and it is both of our first times. We have tried a few times now, but every time we try we get a little further. it always hurts terribly though, and then it takes so long he stops being hard. We're just going to continue trying, but does anyone have any advice?