What Causes Abnormal Menstrual Bleeding, Mood Swings And Dizziness?

hi i am very confused about my body, i had done a pregnancey test that came up negetive and i had been on my period twicw but very lightly, i have been having very unusual mood swings and hot sweats and some unusual food cravings, i had drank alcohol and getting drunk very easily so had drank less alcohol (5%) and i still got very typsy off that, i am finding it hard to fit into my size 10 jeans which i had no probem with a few months ago, im not eating all that much as i hav had alot of nausea and depression and am exercising alot more so i cant have put any weight on as it it very hard for me to do naturally, i am also having alot of dizzy spells and i am very tired all the time and moody.when i did the pregnancey test it came up negetive but it came up very faint as a positive then disapeard which left me even more confused! i am very unsure on what to think about all of this, i already have 2 boys and me and my financee have been very very brudey lately