I'm rather lucky as I was always overweight (and unlike yourself - not at all tall!) I never had any problems apart from the lads taking the mick - all in good fun though as I was always in the "good crowd" or as we say up here, "the daft lads". Besides, being a lad it would have been acceptable to use the fists if necessary
In a bid to cheer you up, I'll relate one incident to you. A young kid living nearby to me called me fatty, he was very young, so I did the adult thing, and maturely called him "ginger nuts" lol. His big sister was looking after him, and she didn't know where to put her face.
Skip forward until fairly recently, the same little kid, a couple of years older, but still ginger
called me baldy!
I asked him "What was wrong with fatty?" - and he said "Nothing mister you're not fat!" - I was quite chuffed my weightloss had met with copper-tops approval, until he followed it with, "But you have got a baldy heed!"
I wonder if I had been bullied mercilessly like you whether I would have done nothing about it until I was 45.
Anyway, as others have said, there's some nasty people out there, and though it doesn't make it any easier, they are more to be pitied than hated.
Steve