My body doesn't believe in Womanhood

Why do I feel SO Alone? I feel so not a woman. I feel like a reject from the human race. As a species are main purpose in life is to procreate, to reproduce, to copopulate. As women this what we are made to do.Women are supposed to bare children, breastfeed them and nourish them.My body is not a woman. My body does not believe it has this purpose in mind.My Husband and I have been trying for Baby number 1 for 3.5 years, we have had 3 unsuccessful pregnancies. We have spent a fortune in clinics and invasive proceedures, we are 27 and 28 years respectively, we are 30 thousand dollars in debt for our quest for our baby. We struggle everyday to go to work, to make more money, to move along in our lives... But there is always something missing.., We work holidays so other families can spend time together, We send birthday wishes and gifts to all of our friends who have little ones on their special days, we attend showers and christenings, we watch as our friends slowly stop inviting us to their get togethers because we have no children to compare stories with. We know they mean no harm in excluding us, they just have little in common with us now, their children are growing and making steps and they are making friends with PTA, soccer, ballet, etc. I work with 9 pregnant women, everyday I am reminded how unwoman I am. I see pregnant lady after pregnant lady, family after family, all day long.. I often find myself crying on the way home, or trying to find the strength to even get out of bed to torture myself for another day at work. I am now to the point where someone announces their pregnancy, I do not even congratulate them... How do you keep going after this?