DID/OSDD is on the far end of the spectrum and a result of severe and/or prolonged abuse and/or trauma in early childhood.

there are several other types of dissociation that do not include having alters.

you could be experiencing derealization and/or depersonalization which are types of dissociation and quite common in general. they often are a result of anxiety/stress and could be caused from panic attacks too (like you described in the past). sometimes people who smoke weed also experience that (not saying you do) or also medications (antidepressants, etc.) you also might have maladapative daydreaming.

you can learn grounding techniques which you can find by doing a google search. there are a lot of useful ideas for those.