How can I work on pitching alone?

I’m new to pitching this year and I want to work on pitching during the off season so I can do good during the spring. I go to pitching lessons once a week and I have a lot of trouble with mechanics and control. My pitches are always too high and far from the strike zone and I can’t control where my pitches go. I also don’t know how to use my lower body and core to increase velocity on my pitches. I don’t have any friends to play catch with and it’s always raining a lot so it’s hard to go outside and practice throwing off a mound. No one in my family is athletic or knows anything about sports so I don’t get help. All I have is my glove and a baseball. If anyone knows how I can work on my pitching mechanics and control in the environment I’m in right now and list some drills and the name of them and how many sets of reps it would be very appreciated.

How old are you?

I’m 15.

I would suggest that you throw at least one other time per week to start with. It doesn’t have to be a lesson. You just need a place where you can throw a ball at a target of some kind like a net that you have taped a target onto, for example. As far as throwing too high. Reduce your distance to target and try to get on top of the ball and release the ball out in front of you. Work on that feel and slowly increase the distance again to get back to pitching distance. In your bullpens work on the bottom edge of the strike zone to reinforce your feel for this type of pitch and delivery.