Help please!

So my husband and I are trying for baby number 2.

I’m currently 18 days late for my period which means I did not have one the whole month of March. I also have taken 2 pregnancy tests which were both negative.

What should I think? Should I call a doctor?

This also happened at the beginning of the year where I missed the whole month of January but I did have one in February and now I’m back not having one in March….

I have never had this issue before:(