Hey FrancoL,
I think your intuition about the rate that you were loading the bench press and how you were doing it are likely contributors to your situation. Some other things are contributing too, but nothing you've written above jumps out as a red flag that would require more medical attention than you've already had. It sounds like your experience is a typical persistent tendinopathy. These types of issues tend to linger, and the rehab process for managing them is full of ups and downs. It is not linear, like a cut or a broken bone.
One important thing to note here is that it is ok to feel pain when you are rehabbing. It sounded like when the pain emerged, you took a push through strategy and had a pretty bad exacerbation, but since then, you have been using more of an avoidance strategy, staying away from things that make it hurt. The ideal strategy for managing something like this is between those extremes, and I call it a nudge strategy.
Another thing going on here is that you seem to think that something must be damaged because you have pain. This is not the case. It is more productive to think of pain as an alarm telling you that something might be in danger. Sometimes our alarms are too sensitive and signal that something is threatening when it is not that big a deal. It's like the house alarm that goes off when a mouse runs through it. The mouse is a problem that needs taking care of, but the purpose of the alarm is to detect burglars; thus, it does not accurately reflect the danger of the situation.
To manage this, I would use a linear periodization approach by starting to press and bench lightly for higher reps (say 12ish) and gradually decrease the reps and increase the weight over the course of 12 weeks. Working up to a top set or two and doing 3-6 total sets after the bar warmups. The goal here is to be 85% better in 12 weeks and feel confident managing your situation in the future. The goal is not the total elimination of anterior shoulder pain forever. I can't help you with the latter goal, but I can with the former. Giving you a specific detailed plan for dealing with this is beyond the scope of this board. If you are interested in a consult or more regular online guidance, check out my website here: Emerge Stronger
I hope this helps!