Help, looking for new insurance

BACKSTORY: I turned 26 last year, and I’m a contractor at my employer. They changed what company I’m contracted through, and I kept my insurance from my previous company. I discovered that insurance was garbage and cancelled it before I looked into the new company’s benefits. [Frustration impulse, but the company didn’t try and stop me at all, so I’m assuming this happened a lot lol] By the time I looked into it, I was past my new company’s date of being eligible. I’m trying to get new insurance, but I really don’t want to get scammed. I’m in TN and don’t qualify for Tenncare. I’m looking for something that’d have mental health care since I’m on antidepressants and need a new therapist real bad.

-My partner makes $1800 a month and I make ~$2100 a month. For some reason the marketplace gives them really good insurance starting at like $50, and my options start at $200. We live together, but we haven’t lived together long enough to qualify for domestic partnership. If anyone has any insight as to why this might be or if I can somehow use their insurance, I’d appreciate it.

-I put in my info through ehealth, and their silver plans start at $50 for me because of Cost Sharing Reduction? What is this, is there a reason the healthcare marketplace doesn’t offer me this as well?

Thanks in advance!