When I was pregnant with my DS I had a pressure feeling Low down from about 20weeks, I was told this was just due to growing, stretching and my baby's position (he was breech) I had the constant pressure all the way up until birth, this time round I dont have any pressure I don't know if it's because my baby girl is head down or just because im carrying a little higher, personally I'd think I'm sure there's nothing to worry about but I do know once you've got yourself worried it does help to have some reassurance from a professional, so IMO I'm sure everything's great bit I guess it's no harm just having a check with your mw or doctor in the morning,
Hope you don't worry too much..x