You wanna be a bodybuilder or a powerlifter?
Unless you need to be breaking records.. stop chasing a number and instead focus on developing a more, well rounded routine. If you really need to know how much you can max bench, check it every month or two, not every workout.
Damaging the shoulder as you're starting to see, will always come back to remind you that you fucked up. Considering you're post injury already you have even more of a reason to back off a bit.
In my opinion, I'd flip to working out with lighter weight and focus on control, form and rep timing. On bench, make sure to never lose your shoulders, smash them blades together and since you're lifting with someone ALWAYS get a lift off to maintain proper posture. Only go down as far as it takes to make your elbow line up with the shoulder, no deeper. Maybe look into pyramid or reverse pyramid training so you'll have more of a build up of weight instead of the same thing 5 times. And most importantly focus on the quality of your repetitions, slow down with the weight, and explode up.
Hope this helps a little bit