Yes. You can stop. It’s important that you learn now, before you do permanent damage to a promising relationship.
I’m sure you already know that the jealousy has nothing to do with your girlfriend. From what you wrote, she isn’t doing anything inapporpriate. The problem is inside of you. Your insecurity and/or low self-esteem is getting in your way and is showing up as jealousy.
Do you feel you don’t deserve the girlfriend? Are you convinced that you aren’t attractive or interesting enough to hold onto someone who loves you? Are you sure that rejection is the end of the world and that you can’t handle that possibility? The common denominator of all of them is fear — fear that you aren’t quite enough or don’t have the skills to be in a close relationship. Those are ideas, beliefs, and attitudes that you need to work on.
Your fears will not be reduced by controlling her activities. If you make controlling demands, she will eventually do exactly what you fear: She’ll give up on you and put as much distance as she can from you.
As a teen, you are not at all alone in these feelings. Jealousy is a normal emotion that everyone has to learn how to deal with as they become adults. Most teens are unsure of themselves when they start a new relationship. Most teens are afraid of rejection.
The teen years are the time when people develop the skills needed to be close to someone and both the self-confidence to risk rejection and the skills to handle it if it happens. If you have friends you trust enough to talk with about your feelings, you will find that many of them feel as you do. Some have better ways to cover it than others. Some have developed enough strength to manage their jealous feelings and may be able to give you some ideas for how to develop yours.
You do need to take a hard look at yourself and try to figure out the root of your fear and what you need to do about it. If you can’t do that on your own, do consider seeing a therapist to work on it with you.
In days of social distancing, you may not be able to find a therapist who will work with you face to face but many therapists are now offering online therapy. You can also join a forum here at Psych Central. The forums are social communities of people who are struggling with the same issue and who offer support and advice to each other. There are also several self-help workbooks on building self-esteem for teens available at bookstore sites. Working your way through one of those is also a good place to start.
I wish you well.