My periods are crazy

my youngest is 2, my periods are crazy I had one 2/17 then not again until 6/17 now my last one was 6.5 weeks ago, my tubes are tied but I guess when I miss it or am late I kind of get excited that I may be pregnant but then if I am have to worry about if it made it to my uterus . 1) Has anyone had issues like this 2) Why does a part of me want another baby so bad when tying my tubes was a mutual decision. I've had millions of lab tests all normal :/