I never wanted children. I was scared of childbirth. Petrified. I couldn't talk about it, couldn't listen to friends talking about childbirth and I had never held a baby or felt maternal. I was your age when an obgyn I saw for endometriosis said "if you want children you had better start now" I panicked and now I have two DS.
I did everything, I gave up work, I did HE for years, I rarely had time to myself, I resented their father (for other reasons) however I've never regretted a thing. Mine are 12 and 16, to me they are the most fantastic humans I've ever met, their father and I are not together (thankfully)
I did it all wrong, no romantic proposal, no shared childcare with ex, no planning......but hey, it's worked out fine. I never needed his money and don't now. Being married would have necessarily lead to divorce.
You must do what's right for you, I just wanted to illustrate that it's possible to get over the fear, it's possible to find yourself quite happy despite the sacrifices, and it's quite possible that your relationship married or not may not survive, but if you do have DC you have a commitment that is far more enduring. And I've rarely met anyone one else who has said they regret having children. For most love seems to outweigh any negatives.