I think when you're starting at the bigger sizes it takes a while to move into the next one. However, you should really go try on some new stuff and see and bring someone with you! They will be able to tell if something fits you or not

I found that sometimes I would get used to the loose fit of my pants before realizing that hey! I needed new clothes.
I found that my first 20 pounds (200lbs to 180lbs) I barely went down a pant size. However once I passed into the 30lb territory (170lbs) I started moving down pant sizes pretty fast. I think every five pounds or so I would move into another one.
For some reference:
- I started ultimately at size 16/18. With just exercise I lost inches and got to 14/16
- at 180lbs I wore a 12/14, mostly 14.
- at 170lbs I wore a solid 12, sometimes 10 (a stretch)
- at 165lbs, I wore a 10, 12s were getting baggy.
- 161 lbs (now) I'm not quite sure, but I did fit into a size 8 recently and then a pair of size 9s. My old size 11 dress fits perfectly now too. I'm guessing I'm an 8/10 now, 9/11 in juniors. I'm not buying anything unless it's cheap because I keep going down!