Skipping ahead real quick (I’ll go back and read the whole thread) to share my 190 lb, 5’7 to 5’8 self on my 14.3 pony and my 15.2 horse, for OP’s reference.
The buckskin is 14.3, the gray is 15.2. Neither care about my size, and I think I look fine on them. I scored a 71% in Training 3 on the buckskin a couple weeks ago, so I don’t think the dressage judges care either