I can not give you anything specific as I do not know your history or where you are at now. But if you have moved on from the physio and are ready for exercising again I can give you some suggestions for your training. Hopefully your physio went through a lot of activation exercises to work on activating the right muscles when performing exercises as well as basic strengthening.
Firstly, you want to start of by working on being able to use your scapula properly. If you do not have good scapula positioning and control all the external rotation exercises will not be of use as your shoulder joint will still be in a poor position (stretching and weakening the external rotators). So you need to work on stretching your major internal rotating muscles and in specific your pec minor and major and anterior deltoid. In conjunction with this you need to strengthen the scapula retractors and depressors which are mainly your rhomboids and lower and mid traps.
You should be looking to be doing 3 times as much back work as pressing. Cut out benching and dips (which I see you can not do) and anything similar. If you have been to physio you should be able to do military press (light weights) for learning scapula control. Basically you are focussing on making sure your scapula moves correctly whilst you perform a MP. You can also do this with lateral raises if you have serious issues with the MP. Your back exercises should include a row (seated, bent over, t bar), a unilateral dumbbell row and prone t's and y's (reverse dumbbell flyes). You can also swap in some band pull-a-parts or face pulls for one of the rowing exercises if you would like. For now that should assist in getting your scapula issues corrected you should be looking at doing that for at least 8 weeks so that your issues are far behind. If you have sufficient scapula strength and control by then you can reduce the pull to press ratio to 2:1 (reducing one row). You can do the external rotation exercises the way Fadi has suggested outside of the gym, just do not over do them so low weight or use therabands and focus on the contraction and utilise higher repetitions for now.
I hope that helps.