I'm seven months in on HRT. One of the first things I noticed was my sex drive decreased, but now it's coming back for some reason. Does this mean they stopped working?

not sure, but i don't think so. Relax, it's okay.

I would talked to your doctor.  Sometimes there is a pause for some reason.

My sex drive went away to start with.. And then later came back, but it was different.

Remember baby, they work in cycles just like natural hormones. Some weeks you see results, some you don't. If it last's too long definitely get it checked. Here's a BIG HUG to get you through.

HRT makes you chemically female.

Females have a sex drive (or else the human race would have died out thousands of years ago).