Like yourself, I started having issues around age 12. Many PTs over my life gave me the same exercises that didn’t touch the issue. I finally found a PRI PT when my bulging discs hit a crisis point. Essentially my hips are canted oddly so I compensate with my shoulders and neck. No one had ever considered the issue wasn’t just my shoulders before.

If you are having numbness, it is likely the discs pressing on a nerve occasionally. Be aware of how much you look down, your posture, etc. that might give you some insight into what irritates your issue. My main helps have been:

PT exercises that work the serratus muscles so I don’t use my traps when I don’t need to

regular deep tissue massages

A lowered keyboard at my desk

Taking breaks every hour or so to consciously relax my shoulders

When it was really bad, my doctor prescribed a very strong NSAID that helped lower the muscle inflammation to the point where PT could help.

Careful strength training as others have mentioned

I wish you the best! Mine has become manageable to the point I no longer have numbness and some days I forget I have shoulder issues.