VENTING! ugh!

I haven't been actively trying to get pregnant, but my husband and I haven't been using any protection in the last year, and I've never got pregnant. today I'm a day over 3 weeks late for my period, and my test are all negative. I had dream last night I had a positive test and when I woke, I took my last test, and it was negative 
​I started having lower back cramps, and I feel like the period will start today. 
​I have a 2 year old, I've always told myself and my husband, I have a child, I will not be selfish and scream to God why can't I get pregnant again, when others can't get pregnant with there first.