Welcome to the site. Your velocity is generally average for a HS pitcher. Since you are just a rising sophomore and 6'2", you likely have potential to gain quite a bit of velocity. It is a tricky thing though. Some just stop gaining much at that point and some gain quite a bit. Control what you can control. Make sure you are getting good mechanical instruction. Make sure you are on a strengthening program suitable for pitchers. Work your arm but don't overwork it.
There is a wealth of information here that can help you. You can search threads by topic or continue to ask away. Congratulations on finding this resource. Keep finding resources that can help you and put the information into action.
Oh, and don't get hung up on age. The best way to look at it is that you are a HS pitcher now. Aim to compete with other HS pitchers, not other 15 y.o.'s. Some HS pitchers your age are touching 90 and getting recruited. Some will improve a lot over the next few years. Some won't.