Help!! I'm so confused.

[Mommabear91]

I have a 13mo old. He was BF until the week he turned 1. I haven't BF since about the second week of January. My AF has been very regular since he was about 3mo old. I have a 28-30 day cycle. The last three months I have had spotting, sometimes before my AF sometimes after. I've been having a lot of pregnancy symptoms the last 2 months. ie; occasional nausea, headaches, lower back aches, some food aversions, frequent urination, some cramping, fatigue, mood swings, my lower abdomen feels harder..etc. My AF was from Feb 28- March 3..and the last two days I only spotted, didn't even have to wear a panty liner. I have taken 3 Clearblue digitals and they've all been negative. I at first thought all the symptoms were from my hormones balancing back out from no longer BF'ing, but I have had 2 children and I just feel pregnant. I'm going to try a FRER in the morning as those are the only tests I've used for both my pregnancies. Is it possible for a certain test not to work on some women? Why would all this be happening if I'm not pregnant?! Please help! TIA!