Taking your template, one presssion model I really like is:
Depending on how you performed:
5 reps: +5lbs
6-7 reps: +6lbs
8 reps: +7lbs
or similar (you need microplates). So you get extra work in when having a good day with extra reps and the workload will be heavier next time around.
But be aware that you'll probably have the opposite problem to what you're facing pretty quickly.