Finally positive!

My period is 2 weeks late. I've tested a few times and they were all negative until last night and again this morning! I had a miscarriage last year, and that time I tested positive 4 days before my period was due. I even had a blood test 5 days ago after they found a tiny spot in my uterus on an ultrasound, and it was negative too. Is this normal? I've had pretty rough cramps on my right side since a few days before my period was due, and finally within the last few days I've had pregnancy symptoms the same as I did the first time so I decided to test again. They're definitely positive I'm just not sure why it would take so long to show up. (First pic is last night, second is this morning)