Typically at 5-6 months is when you begin to "pop out" and maternity clothes becomes more necessary. If you've only gained 7 pounds so far, you still have a ways to go! (I think I'm up to about 40 now, and have 5 weeks left today -- ACK!!!! I need more time to prepare!!!!).
I was able to get by with a lot of drawstring waisted pants that I already had (so the legs still fit and I just had to keep letting out the tie) but I think half of the weight I've gained has been in my chest! It's unreal! The tops were the first thing I had to invest in. Yes, they are like tents, but hey, they fit!

And yes, maternity clothes makes you look WAY more pregnant than regular clothes, but by the time you need it, you won't care.
I'd avoid the mall chain maternity stores like Motherhood because they're really overpriced.
If possible, check your fiance's closet for shirts (and maybe even pants depending on what size he is!) and see if you can raid a few things from there. I borrowed some of my husband's polo shirts and t-shirts but his pants are still way too big (thank goodness!)
My sister is a huge bargain shopper and also found me a few cute things from thrift stores for like $1 a piece! It makes sense because people that go out an buy full maternity wardrobes only need the stuff for a few months and then they tend to never want to see it again!
Another note: don't go out and buy any new shoes for a while. Right now I am wearing a full size bigger than usual. I hope my feet go back to regular size afterwards -- because I love my shoe collection and don't want to think of giving it away!
You'll see -- the time between now and February will fly by. Just wear whatever makes you comfortable and happy!