If I’m not good at shooting or with PT, is there any way I can reclass from 11B into an MOS that I will actually enjoy and be useful for?

Both of those are skills that can be learned, give yourself a chance to learn and grow before quitting. Sounds like you need a resiliency class while your at it.

What needs to happen is an NCO needs to take you under their wing, and mentor you in getting better at PRT and BRM.

When it’s time to reenlist you may have a chance to reclass. It it will be several years until you go to your new training. Until then you still need to do PT and shoot. Shooting and PT are skills you can improve in your own. These are Soldier skills and there will never be a time or an MOS that they are not important.

Ironically, you’ll need those skills even more in other MOSs to get promoted. As an 11B you can still make points for SGT and SSG even if you just meet the minimum and you’ll get promoted. In most other MOSs you’ll have to score close to the max, or even max it out, to make enough points to be competitive for those ranks.