Help!!! I need tips please

I was using the IUD (mirena) birth control for the last 3 ish years and I know my OB-GYN told me it could take up to 6mos to conceive once I have it removed. So, Oct 2018 I decided to have it removed so that my fiancé and I could start trying for our first baby together.

(I do have a nine year old son already so I know I am able to get pregnant ☺️)

Well my cycle was supposed to start 4 days ago and I haven’t started nor had symptoms of starting. I decided to test today and got a negative.!?! I’m normally on time within that day or the following. Is it too early for me to be testing 4 days out or should I be waiting a few more days.?????

I’m so confused!!

Anyone have negatives within those few short days of a missed period but still came out pregnant ??? 😵😵😵