I accept that and I'll have to simply have to train and diet even harder to be better next time I compete
You peaked as far as muscle mass a long time ago. You are competing against guys using lots of OTC hormones, at the very least. You need drugs on top of getting leaner. You wont put on any muscle without hormones, and even if you did manage a pound or even two it wouldn't be enough to do better. Since anything OTC is fine you have a lot of options still, without breaking the silly rules. You could do a shitload of a nonmethylated oral, lather up your body with the transdermals too, one or two 17aa orals like Superdrol, DHEA, antiestrogen like Novedex XT, a thyroid analogue, stimulants like dimethylpentylamine etc.
You wont make any real changes without drugs. That's the cold hard truth.