With your first pregnancy, how far along were you when you started to really show?
And kind of a related to this, when did you need to start wearing maternity clothes, especially pants?
The sooner you switch, the happier you'll be. I promise you! I held out for far too long in my first pregnancy and was miserably uncomfortable. Sorry, it's been too long for me to remember the exact weeks etc. With Abby, I know I just went up one size on a pair of jeans until I could wear "real" maternity. I liked the long and lean jeans from Gap. I forget the terminology but I didn't like the jeans that had a huge elastic panel at the front with Abby. The Gap ones went all the way around but were really low. However with Emily, I carried so low I really did need the kind with the full panel to be comfortable.
You really can't "show" until about 12-14 weeks because the uterus doesn't rise out of the pelvis until then. However, there's a lot of body fat being laid down for the baby, even in the 1st tri. Depending on how you carry your body fat or water weight, some of that may be centering on the belly, making your clothes uncomfortable sooner rather than later. Fear not! The bloating will soon give way to real baby belly and it's perfectly natural and normal. I used to pat my baby fat all the time!!
I got the bloat bad from about 8-12 weeks, so I decided after being so miserable to just go ahead and switch to maternity pants at around 10 wks. I never went back to fitting in my regular pants, it switched from bloat to bump without any decrease in size between. My bump started coming in about 12 wks.
All of my pants are Gap, mainly b/c I'm short, and they sell short sizes. Like Taytee mentioned, I like their long and lean and 1969 maternity pants. I bought two of the lower band style, and 1 of the full coverage style. I like the look of the full coverage more, but i find myself pulling them up a lot more than the other ones. All 3 look just like regular gap jeans . . . so i say if you're getting uncomfortable, definitely go ahead and buy a pair or 2. Gap is ALWAYs running sales, so you can usually get jeans for 20-35% off the reg price.
For tops, I think I got away with wearing my regular flowy tops until about 20 weeks. I'm short waisted, and just plain short, so my shirts started looking like crop tops about then. I got by wearing a tank underneath some of them for awhile, but finally gave up and switched over to maternity tops. I mostly wear tops from the Loft, Gap, Old Navy (they have the best rib tanks).