Don't worry im sure all is fine. If you worry about measurements and compare your baby with others you will end up a nervous wreck!! just get on with what you're doing, eat healthily and don't look at the figures! If there was a problem, the midwife would definitely tell you.
Trust me (and it's easy to say now) but you will do this comparing and worrying when baby comes as well, but after you've settled into your routine, you will forget all the other babies and realise YOUR baby is not every other 'perfect' little baby you read about. Look.. I was accused of overfeeding my baby because we chose to take her to A&E as she vomited in her sleep and panicked herself (she was fine, but we were worried and wanted to be 100% sure she was alright). Apparently we were in the wrong because we gave her 130ml of milk instead of 100ml!! that was rubbish though, they just needed a reason to explain a bit of a sickly baby. It panicked me loads at the time and up until recently I was always worried I was "overfeeding" her.
(By the way, I know you weren't talking about when baby is born, but im just trying to show you not to worry, I couldn't give a crap about those idiots saying we were overfeeding her now lol). Im sure you will do the best job you can with your little one, and the baby has to come out so don't worry about how big it is, Bethanie was only 7lbs.. but shes very long now, so heavier than a few babies. As soon as they crawl etc, it will fall off.