It's been six terrible years 😕

I was with my ex for almost 4 years and when we finally was ready to have a baby. We was trying and trying and nothing ever happened. I when to my doctor and he did some test on me and said everything looks fine just to wait cause I'm young ( at that time I was 21). Eventually we ended up breaking up and he gets with another female and in less than two months she's pregnant :/ I was so confused cause I was with him for almost 4 years and nothing ever happens..... So time pass and I met my fiancé I'm with now. We going on 2 years and I'm having the same problem :( I feel like giving up but I want a baby soo bad 😕 any help !?