ill be 35 weeks tomorrow and i just started showing like 2 weeks ago. im STILL wearing my prepregnancy clothes...jeans included (sometimes they can be zipped and other days i need to wrap a hair band around the button and hold to close them....i was worried but i asked my doctor when i went a few days ago and she said that im doing perfectly fine.
every single pregnancy is different from the next so im sure youre fine too....if youre really concerned though, ask your doctor to be sure.....and dont forget the vitamins.

good luck momma.