Pregnancy ...envy

So I'm 31 and we've been ttc for 6 months now and I really thought this month was going to be my lucky month, it wasn't. Last night my husband and I were out having a good time and then I saw a beautiful pregnant woman and her husband and I had this wave of emotions. I became sad (had to keep myself from crying) and envious of this pregnant woman, I have never felt that way towards a pregnant person until last night. I feel like a bad person for feeling like this, and even worse because I don't know what I'm doing wrong or what is wrong with me. I just want to be pregnant so badly. :(