Your boyfriend is a lucky man indeed to have such a loving and supportive girlfriend. But from what you said, I think you are in over your head. He is in treatment with someone who is trying to adjust his medications. He needs to be working with his treaters, not with you, if he is feeling so symptomatic that he is seriously considering a hospitalization. I’m also concerned about the “blank” times. I hope he has shared this information with his doctors and that they have ruled out the possibility that he is having absence seizures.
If he really wants you to be helpful, the best thing your boyrfiend can do is make you a member of his support team by including you in his appointments. That way, you can report to the doctors what you observe about his moods and behaviors. Your boyfriend can only report what he experiences from the inside. You can be a more accurate reporter of how he appears from the outside. It would be helpful if you kept a daily log of your observations to bring along to the appointments.
I understand that you feel strongly about each other. But it’s really early in your relationship for you two to be deciding that you are a forever couple. Your boyfriend needs to focus on getting himself together before he will be able to be the kind of partner he wants to be and that your relationship needs. Although you show yourself to be unusually mature for 17, it is still a lot for someone your age to be a support for someone who at times is unable to be an equal partner. Pressure to take the relationship to the next level may be too much for him to manage – regardless of how much he likes you. I hope you will both slow down a bit and give him the room he needs to truly heal. Sometimes loving someone means taking a step back.
I wish you well.