Working on your worthiness before entering a relationship I think is a must. Or really give it some effort while working on the relationship. I understand where you are coming from. I felt if I wasn't worth it for my ex to stay right after having our hard-fought for child, I must not be worth anything.
I share the same exact fears as you regarding sacrifice.
I have realized that to the right guy you and your child won't seem like so much of a sacrifice. It's in the perception. Being with you and your son through the good and the bad may seem like a dream to him, seriously! it may be what he wants in life. A family.
I do think we sacrifice when we have kids, but I view it more as a trade-off in some areas. Life may change, but people welcome that change.
To speak to what Zues said, I do agree. Sex does not have to go away. Date nights might not be as often, but they do not have to go away. There may be just as much joy in going apple picking with you and your kid as there is hanging out at the bar. I realize that with the right guy, that's the way life would be. it is realistic. I know a good deal of guys who are like that.
And Zues, there are women with a very good sexual appetite. Yes, our sex drive is fueled differently than men's most often. But it isn't a chore to all of us;)