I've been through the same situation. Weightlifting is not the reason for gyno and bjj wont help fixing it.
Avoiding going into the causes, I advise you to train smarter. First, you would want to widen your pectoral muscles and add more mass to them, cuz wide pecs can really make your gyno look insignificant. For this, you must never lock your elbows in any of your excercises, i.e. do not rest at the top of all pushing excercises and keep the tension constant. You would like to use lighter weights in than usual and increase the weights every week.
Secondly, keep a tab on your diet. Use a good whey protein for muscle gain.
When above things are in check, you must try shredding the shreddable fat on your chest. Skipping gave me good results. For cardio, do sprinting few times a week.
Many people with gyno actually just have losable fat on the chest, others may have some developed glands, thats what 'real' gyno is. You may have a little but dont worry, muscle would hide most of it.
As for your self esteem, life is too short for that. Most of the endomorphic people out there have some gyno, sometimes we become too self-concious about it. Dont think too much and work hard.
I think you have a knack for bjj and we know bjj is fun so you need not miss out on that. Keep weight training and bjj in a balance and prioritize as you feel.