Would I qualify for special enrollment and premium subsidies if I lost my employer’s health insurance but was still covered by my parents insurance?

Hello, I’m 25 and am currently covered by stepfathers insurance and also able to enroll in medical insurance through my current job. The problem I’m running into is that because I live in a different state than my parents the therapist I see is out of network. The employer health plan also doesn’t cover therapy. Meaning I’m paying completely out of pocket and it’s become too expensive.

It’s my understanding that if I enrolled in my employer’s health and insurance and then lost coverage because I either quit, got let go, or dropped to part time below the minimum hour requirements I would qualify for subsidies and a special enrollment period to get Insurance through Marketplace.

Am I understanding this correctly? Would I still qualify for premium subsidies if I’m covered by my stepdad? If I got dropped from insurance because I switched to part time, below the required hours, got insurance through Marketplace and then picked up enough hours to qualify for employer insurance again would I still be able to keep my insurance that I got through marketplace? What if I quit this job, got marketplace insurance, then found a new job that offers insurance benefits? Is there anything else I’m missing or should know?

Thanks so much in advance.