Hopeful but afraid! 27 and TTC for 3 years

Angel
My husband and I have been TTC for 3 years. I'm afraid it's not going to happen. I try to stay positive but I'm 27. Am i to old? He has 2 girls from a previous relationship so the problum has to be me. We want a baby so bad but I don't know what to do if it doesn't happen. I hope this app helps. I am the only childless person I know. I feel broken.