Im tryin to conceive but my periods are messed up so how will i know?

in october i was a week early so ther for in november i shud of bin early again or dead on time but i wasn't i didn't have novembers period until dec the 4th if that makes sense and now january i worked i shud be due on the 1st new years day but still nothin i did two different tests today they came up negative but have been experiencing a slight niggling sort of pain in my lower right side ive seemed irratable and snappy tired but then at nite i cnt sleep atall and my appetite has increased but ive lost weight any suggestions on what the hell cud b goin on thanx adele x