To the OP,
In my 30s (early/late? I forget) I couldn't do a single clean chin. That changed dramatically as my strength increased and body comp improved with training. I'm going on 50 now, and have never chinned as well as I do now (reps across sets). My frame is different from yours (5' 7", ~ 200 lbs), so ymmv. Still, be patient and committed to the long-term. Give yourself years. A coach would probably get you there sooner/soonest; but you'll do it on your own as well, with time.