Help! I ordered a bunch of stuff from Carter's a few weeks ago and I'm currently obsessing about whether I got the right size.

I ordered an 18 month for his swimsuit and rash guard. At the beginning of summer, T will be 9 mos (he was born in August). We live in the South so summer is usually May to September.

He is currently wearing 9 mos Carter's and is in a mix of 6 and 9 mos in other brands. He is about 19 pounds. He is in the 75th percentile for weight and 80th percentile for height.

Would you send back the swimsuit and rash guard for 12 mos or keep the 18 mos?

Some factors:
1. He will be spending TONS of time in / near water - we have a pool and a lake house. Don't judge, but I want him to look adorable... I worry a huge swimsuit will impact this.
2. He has grown like gang busters his entire life. To put his current weight in perspective, he was born 6 lbs 13 ozs.
3. He is EBF - I think this plays a role in growth slow down, but I'm not sure?
4. We will have access to a pool in the fall.

Thoughts? If you got through this, thank you - I realize this isn't a big deal, but I have been obsessing (first time mom problems / first world problems)