Starting to be worried

Hi, im new to this. But starting too feel really lonely I've just turned 20 and I've been with my partner 3 years he is 33 and I have not been on contraception, we don't have sex often maybe 4 times a month. But I really want a baby, I am starting to feel so alone everytime I try and talk to somebody they say im only 20 and ill have a baby one day. But nobody understands the worry that I'm facing and just how upset I feel, That maybe I will never have a little life off my own, I just need somebody to talk too everytime one of my friends tell me there pregnant i feel envous and thats not the person I want to be. I even try and put other friends off having kids because off my problems and feel like i cant be happy for people. Please can somebody tell me why im becoming so jealous and horrible? This is not who I want too be