Still no pregnancy :/

I thought I was pregnant a couple of months ago because I was almost a month late and had symptoms. I wasn’t. But now it’s like every time my period hasn’t showed up my fiancé always assumes I might be pregnant. I know he wants to have kids but I don’t ever want to get his hopes up because then I feel like a shit person because I haven’t been able to get pregnant. I feel kind of lost because I don’t know what actual tips there is besides “have fun with it” “be patient “ I mean yeah I already know that and we do have fun but what are some tips to help us actually GET pregnant. Also all of my Facebook friends are posting about having babies and getting pregnant and it just makes me so depressed😞💔 please I’d love some advice. I can’t get tested to see if I can have kids until I’m 21 so I don’t even know if I can have kids. But I want to have as much help as possible