My GF was a single mother working minimum wage when I met her. A couple of years older than me on top of that.
And I'm not some poor and/or ugly dude who had to settle with someone with kids. I have a pretty decent career, I make more money than most guys my age and most people will tell you I look good.
Most people are surprised I ended up with a single mother and not some superficial bimbo.
So it's certainly possible to be someone again when you're a single mother. You just have to realize that your stock went down a lot from a male's point of view and focus on other strengths. It is up to you to explore those.
The first few times I saw my GF was because frankly, she was really open sexually and I felt like could tell her ANYTHING. She wasn't offended by anything. But after a while, what kept me going to her place what her down to earth and no-game attitude. Most girls in their twenties play mind games. I also liked her drive and confidence...she went from minimum wage worker to a very successful business owner. I also enjoy her intellect.
My GF knew an other man's kid is a big turn off for a guy and she is extremely good at reading me and handling this. She didn't become defensive when I appeared distant because her kid annoyed me. For instance, she would get a babysitter and suprise me at my office all dressed up, ready to go on a date. She allowed me to have my own rules when I moved in with them.
Today, I'm a lot more involved with her kid and all his fine, but I give big props to my GF for being able to juggle with three people's totally different situations (hers, the kid's and mine).
It can be done, but you'll have a hard time finding a decent man being a single mom without having something to balance it out. Sorry.
Here's a good start...most young single girls without kids are needy and feel entitled to the moon. Not all of them (the good ones are already taken) but many of them are high maintenance. Just being the opposite of that will give you a good boost.
Also, try to keep in shape. My GF is in very good shape and she's 30 while nowadays, a lot 18-25 girls are freaking fat and they have no kids yet!
Anyway...enough rambling...just know that you aren't doomed