can anybody help me with any tips or people to see to help me get pregnant?

My story is I was told when I was younger I could never have kids and then found out bc I have back problems I probably wouldn't be able to give birth natural but I think that's wrong but then with my ex of 10 years I never gotten pregnant and then we split got with my fiancé in 2015 and I just miscarried last August in 2016 and I didn't even know I was pregnant I kept taking tests like crazy and finally got 4 positives it took me a month to get into my obgyn and by that time there was no heart beat or anything in my ultrasound and my doctors said that is bc I had already passed it before I got in to see him... any tips or ideas to help me get pregnant? I'm almost 27 and I have no kids my fiancé has one.. my obgyn doesn't know why it's so hard for me but it's a 50/50 chance and it's breaking me down to the point I don't even want kids any more and all my friends are pregnant and my two best friends are pregnant and it's makes my emotions super high...