If you have access to a counsellor of any kind, you could always talk to them about what boundaries are healthy and when, and they would possibly be able to help you uncover why you have issues with boundaries. It might also help to read up on the topic of personal space and boundaries, and write down what focuses you think would be both possible and effective (ex. setting limits on how often you text a person in a day excluding emergencies, making plans with different people so one person doesn't feel overwhelmed, etc). Developing independent interests, like a certain subject or book genre or sport, might help you enjoy a certain amount of space to keep you from wanting to be with a person too much. Finally, it can never hurt to talk to them and try to get an honest opinion of what kind of boundaries they want, and checking in every so often, so they know you want to improve, and care about them being comfortable.
