Weird fullness

I am officially 8 dpo. I have been getting this weird full feeling in my lower abdomen. My AF is due 10/25, I have NEVER felt like this before my period. Now I have felt like this when I was like 5-8 weeks pregnant with my boys before but this is too soon to notice something like this right? Anyone else feel like this? I am peeing constantly but I still have that feeling after I am done. I took a cheap dollar test today and of course BFN...but this is freaking me out. Anyone?