Size of baby clothes??

So weird question! With all the summer stuff going on sale now I have been buying for next summer and the summer after for my unborn baby. I know it's hard to guess what size they will be in. But I've been told baby/kid clothes have gotten a lot smaller then they used too so by size baby could be 12 months and wearing a 18 month outfit. I bought ahead with my first but that was 9 years ago and she either stayed on track or was smaller. However she is a peanut. Her dad is a smaller guy. My husband now is huge 6'6 300lbs and I'm no small fry either. I'm 5'6 usually 130-135lbs (not pregnant.) So I'm wondering what size should I buy my sept 1st baby for next summer? Has anyone else noticed outfits are made smaller then before?