Hey bro! Food for thought, take a look at my shoulder workout from the other day and give that a go, i like to pre fatigue my delts before presses as it gets a lot more blood in them before I start to press (I have crappy shoulders too and this helps a lot). Let me know if you have questions on any of it and I will get you sorted. Pm me for cell #.
I find shoulders can be rough to get pump in and last workout the pump was insane