Hi John, welcome to Baby and Bump.
You're still very young, too young to be giving up on things and labelling yourself as a 'loser.'
Going by what you have written, you obviously don't want to be a loser or let down your girlfriend and baby. You seem to really want to change your situation, even if things haven't worked out for you in the past.
Don't just give up on yourself. Only you can determine the path you are on and if you just say, 'well, what do you expect, I'm a loser' then that's exactly what will happen. Even if your job does end at Christmas, work really hard at giving a good impression and learn as much as you can from the work. Then if the work does end, you can move on with more confidence and with a good reference from you ex-employers.
My sister lost a lot of jobs when she was younger due to low confidence and nerves, but she didn't give up and is now doing really well in a job that she has held down for three years and is happy with her fiancee in their new flat.
You can do it - just have faith in yourself and remember, you have a new little person who will soon be depending on you.
Good luck