shouldn't be this hard

I'm doing my hpt tomorrow morning, but I just feel like it's going to be negative. Its been 18 months ttc and I've seen many women on here trying for years and I wish I could be ad positive as they are. I just feel like it shouldnt be this hard to get pregnant. :"( I'm just so tired of the dissapointment I don't even want to try anymore. any words of inspiration ladies or anyone feel the same as me?