No you can't tell, and people should shut-up. Your MW is checking your fundal height, that is the best way of telling growth - everyone else is just observing how much you're poking out compared to other people they 'think' were at the same stage, which has nothing to do with anything and can vary based on your tummy muscles, your height, how much fluid you're carrying, you're frame etc. Some women with smaller tummies have big bub's and some who are very large have small/average size bubs so it's hardly a good indicator of anything.

I don't know why people think it's ok to comment on your tummy size when you're pregnant it's just as hurtful as commenting on your weight when you're not pregnant. People were constantly commenting on how 'small' I was and that made me feel really bad, and one of my g/f's pregnant with her second is carrying much larger this time and people keep commenting on how 'big' she is and 'are you sure you're not having twins' which is, hurtful to say the least. Pfft to them all. Your belly is growing and is beautiful, try not to let people's insensitivity upset you.