Clothing size confusion?

i am 22 and a new mother to a 7 month old baby boy. in high school a weighed 125-135 pounds and wore a size 8. it's only been 4 years but i weigh the same now yet am somehow a size 2/4. i don't remember my measurements back then but i wear the same brands now as i did then. has vanity sizing changed that much in 4 years or am i actually smaller?