I am 28 weeks and this is pretty much how maternity clothing has gone for me:
At 10 weeks, my pants started getting tight. I tried larger jeans that I already owned, but they just didn’t fit right. So I tried my friend’s belly bands, which just never seemed to work. At 12-13 week, I just gave in and bought a couple of pairs of the demi panel pants from Gap on sale. I purchased them in my normal size. They were perfect until I was 16-18 weeks or so. I was still wearing almost exclusively my old dresses and tops, as well.
By 16 weeks, I had invested in a couple more pairs of jeans, but they were from Paige Premium (on clearance) and had a front like this :
I don’t know if you can tell, but they just have elastic at the corners. These are still my favorite type of maternity jean, so I own a skinny pair to wear with boots, and a straight leg pair. By 16-18 weeks, I also had started moving into maternity dresses and tops. A lot of my non-maternity tops were starting to get too tight at my chest, so I stocked up on holiday sale priced clothes at Gap, Old Navy, A Pea in the Pod, and Motherhood. I had also grown into a new bra size.
I thought I was done with maternity shopping at this point, but I am carrying really low, and could no longer wear the demi panel jeans after about week 22. They were just too tight on my belly. So I just wore what I had that did work until about week 26, in which I grabbed a couple of pairs of full panel jeans from Gap on sale, also in my pre-pregnancy size. They have been a godsend and I think they should definetly go through the rest of my pregnancy. I am also up another bra size, at this point, and am anticipating that I will have to change once more closer to time. As for tops, I can only wear maternity at this point, as well as only maternity dresses. I am all belly and boob, so I have no choice.
So basically, it really depends on how you will grow, as well as how you are carrying. Everyone is different. Be prepared that you may have to shop twice and potentially will grow out of some things, even if they are maternity. I have basically been living off of Gap maternity long sleeved tshirts, maternity jeans, and accessories to dress things up. It get monotonous, but at this point, I just want to be comfortable.