If it's budgetable and something you might like, try buying some of the smock-y type stretchy dresses that have been all in fashion for the last like, aaaages. From experience - i had the "do i look like ive eaten too much cake" feeling until fairly recently, so if you can find those sorts of clothes it really helps, because noone can tell any different.
If not, get a sticker that says, "im pregnant you judgemental tossers!". Goood luck!!! enjoy the second trimester ladies, it'll fly by before you know it!
It's perfectly safe to colour your hair in pregnancy, i just wouldn't recommend bleaches or the like, as they're chemical make up is a lot more potent!