Is this something people think when they see a single parent?
I'm not sure what you're using to interpret what they think about you... but I've found that quite a few girls are worse than guys when it comes to simply wanting to get laid. They'll put on a veneer of self-respect to appear to comply with our culture - but half of them will beat around the bush, trying to get you to 'take the lead'.... if you don't - they'll practically try and hold you hostage until they get what they want.
How should I be reacting cuz right now I'm seriously depressed n alone
Well, if you were in my neck of the woods, I'd extend an invitation to my circle of friends' "get ripped plan" - we get together to work out in the evenings on certain days of the week (being the military guy, I tend to be the lead/coach on this) and kind of spend the entirety of Sunday afternoon together with a group dinner (sometimes we eat out, other times we all bring stuff) followed up by a D&D game we have going (because we are nerds, after all).
Something like that wouldn't be a bad idea to try and set up with close friends you have, especially if you can find an environment that is friendly to your kid.
You may be wanting a female half - but sometimes that desire can be destructive to the end-goal, particularly if you come off as depressed/needy. Try to build up as healthy of a lifestyle as you can on your own and with the support of friends, that way you're not craving support (which is hard to find someone who is going to willingly come into your life and provide support with honestly good intentions).
One of the key things to keep in mind when it comes to relationships is that both people have to be capable of contributing to the relationship. Which may be kind of what's going on here... the girl coming into the relationship needs to feel like there is something for her there. She doesn't necessarily want to come in and play mommy to someone else's kid while propping up a guy. That's just the reality of it. She has to feel like there is a future for her to achieve some of her own goals within that relationship (which may very well be to have kids of her own - which is complicated by the one you currently have).
The best thing for you to do is to try and find or build up a group that can help support you without it being dependent upon a marital relationship.