7 months is pretty quick recovery time if you're playing your normal old game in the normal amount of hours. Like borderline pushing the limits.
I've separated my shoulder's 4 times, couple of dislocateds, and 4 clavical breaks. 7 months to full speed serving is beyond my comprehension, as the separates and dislocates took me closer to a year and a half to serve full speed in match play. Even the clavical breaks took that much time.
The twinges just tell you that while you might have all the strength of before, that you are only 70% healed.
70 is plenty to play tennis, but not the kind of tennis that relies on big first serves and head high kicking second serves.