What Causes Pregnancy Symptoms While UPT Is Negative?

i am turning 24 and married with 1yr old kid. i missed my period for about 2 months now since i have my last period on november 29 and until now its already january 29 but still no signs of me having my period.. i feel something unusual in my body, i can feel bubble like movements on my loins which gives me the idea that maybe i am pregnant so i took up pregnancy test, this was during december and it turned out to be negative, my second try is january and still it turned out negative but despite the results i still feel like i'm pregnant cause my tummy's getting bigger and the bubble like movements are still there and this time i feel them more, i also have black spots on the sides of my mouth which are my pregnancy signs during my first pregnancy. i am confused of whats happening.. is there something wrong with my body? i need answers pls.. i will appreciate any. tnx