it's entirely possible that only you can smell it, due to the ridiculous hypersensitivity of the pregnant woman's nose... unless you are hanging out with a load of other pregnant women, of course. i still shudder to remember the stench of public transport when i were up the duff, and as i recall i thought myself quite pongy too. so it might just be that.
If you really are sweating more, try Perspirex. It is amazing stuff. Check with the pharmacist that it's safe for use when pregnant. You put it on at night, wait for it to dry and then wash it off in the morning.
Also I find that Dove original deodorant has quite a strong smell and it overpowers any BO smells!!!