I second the Fjord comment!
There's a Fjord/Belgian cross at the barn I work at and OH MY GOSH. He is the thickest, sturdiest horse I have ever seen in my life [and that includes "The World's Biggest Horse", numerous other draft/QH crosses, and some pure-blooded Fjords]! His legs are literally tree trunks - using both my hands, I can't even reach around his cannons [I have small hands, but still]! He's only probably around 15hh, or shorter, but he easily weight-tapes at 1600lbs.
I wouldn't hesitate to put someone over 300lbs on him, he's that kind of sturdy.
Anyway, that might be a breed cross to keep an eye out for.
Good luck! And good for you for getting back into riding!! :)
Fabio - 13 year old Arabian/Lipizzan gelding
Rest peacefully, Lacey.