Missed period, negative tests

My period is almost 4 weeks late. I have taken 3 pregnancy tests - the expensive digital ones - over the last few weeks and they have all come back negative.

Last time this happened I called my Dr when I was 2.5 months late, they told me they would only see me if I had a + test. Two weeks after calling them, I had a miscarriage. When they did my blood work they said that I was pretty far along (probably 3 months jerks) but couldn't explain why my pregnancy tests were coming back negative. I've had a healthy pregnancy since the miscarriage (my daughter is 21 months) and with her I started having positive tests after 3 days of being late. Since I had m daughter my periods have been pretty regular, maybe a few days early/late here and there but nothing like this.

Anyway, my question is with my history would you call the Dr and demand a blood test? Or would you continue to wait and see what happens?! I'm torn.

Anyone ever have negative tests when they were pregnant??