Work on F2L look-ahead, that is probably what is most time consuming atm for you (I'm guessing). try and get your F2L sub-12.
Yes , correct, you can train this by turning slower at the F2L part,
When I was 21-22 seconds my F2L was like 16 sec ...I just turned to fast to train F2L. Actually when you look at most top cubers at the F2L part they do not turn that fast , but efficient
btw It is not the TPS as some suggested, I turn like 3 TPS still I am 17-18 sec average
You will need more TPS if you want an average like 10-11