Pregnant and unhappy now what?

I'm 29 and married with 4 stepchildren. My husband and I have been married for 4 years with no kids together. I have never been pregnant and have been told by numerous doctors that my ovaries weren't working right. Ever since I was 18 yrs old the same diagnosis so at almost 30 and still no kids I just continued to enjoy my freedom. I had gone back and forth in my mind about why I couldn't do the thing that everyone I know has done more than once. Even my 16 yr old cousin but not me. Trust me other people even my husband made it worse by saying things like" Is my first wife going to be the only woman I ever have kids by? Why can't I have children with someone I love? So I kind of started feeling like maybe I wanted one knowing that in my heart of hearts I really didn't. I think it was more for him than anyone. I never wanted to be a mom because of my childhood. I never had any freedom because my mom had so many kids my sister and I were babysitters. Then as an adult I married into a ready made family;so as much as his kids get on my nerves just made me a little more sure I didn't want any. I made the mistake of telling his mother when I found out because she made me tell him. When I found out I was devastated because I felt that no one would be on my side about not having it. My husband was ecstatic and I was right no one understood my feelings. I am so miserable because there is nothing about being pregnant that is enjoyable. I am actually insulted because people are treating me different as if me being pregnant makes me more important than I was before. There is no part about being a mother that sounds good to me. I don't see anything good about losing my privacy or the spontaneity in my life. My husband says he will help me with the baby and I believe him because he has been wanting one so bad. I just know that with him working I'm going to be the one to bear the brunt of the child rearing. I can't imagine having to take a bag ,stroller and car seat everywhere I go. In some ways I feel like an ingrate because there are so many people that want children so bad and here I am saying I don't want one. I can't help the way I feel. I am so sick of people saying once you see the baby you will feel different. What if I don't? I am 4 months pregnant shouldn't I feel at least a little maternal? I don't think my mind will change it will probably make it worse because I know once its here I am stuck with it and there is no way out. Its usually the man who feels this way but I know this isn't normal and I don't want to make me or my husband unhappy. I don't know what to do because everyday I feel a little more trapped. How do I deal with this dilemma? Does anyone have advice or have triumphed in a similar situation? I am at the end of my rope. Is everybody right am I selfish because I don't want to be a mom?