getting frustrated

my periods are irregular. had a period 2-3 months after getting my birth control out. Didn't have a period while on it for 3 1/2 years. And last Saturday the 25th I had spotting, about 6-7 tiny spots and that was it. The pregnancy tests I've taken are negative. I have a doctors appointment and maybe a blood test on Monday. Would a blood test even work if I was pregnant? according to a due date calculator says I'd be about 4 weeks and 5 days. ( only googled that to see incase I am). I don't have any symptoms other than the spotting and cramps on and off. Feeling down about all this.