You sound like you're experiencing a lot of the symptoms of depersonalization.

Do you have a therapist who you can work with? It might be helpful to learn some grounding skills to first get in touch with your physical body, then start to learn how to connect yourself with your feelings.

I've experienced a lot of the same things long before I knew about having DID. After a lot of therapy, I've started to learn how to connect my mind with my body, but it's hard and not natural. A lot of days I just float about and I have no idea where I am, but when I stop and realize where I am and think about it, it feels as if I've been there forever like what you described with the store.