I think telling your therapist exactly what you've told us is a great start. They are there to help you and there's no shame in sharing that you're feeling isolated and spacey. If I had to guess, you probably isolate yourself and daydream as a result of poor mental health, not the other way around. It can be a side effect and natural coping mechanism for sure to just cut yourself off and get lost in your own world (I do it sometimes without meaning too but stop once I realize bc it's unhealthy). Stims are truly just ways of coping at the end of the day but some are more harmful for you than others. I think telling your therapist is the right move for sure as they can help you identify what specific things make you feel that way and teach some healthier coping mechanisms to maybe avoid it in the future. I hope things work out for you 😁