No period for almost 10 days

I took 3 pregnancy test- all negative! I took one 2 days prior to missing, took one at 3 days late, and one at 5. They were all negative. When pregnant with my other babies I only took a test at 7 and 8 days late. I used a dollar store test for the first test and a brand I never heard of with the last two testing. I'm really not sure what's going on but I plan on scheduling a doctors appointment soon-because I'm really worried something is wrong. If anyone has any advice that be great:) TIA!