2 months no period

so i missed my period in december & january. i’ve taken a test every other week since i missed, all negative up to the one i took this morning. i have started working out more but havent lost too much weight (only like 10 lbs) and started eating a bit healthier. could that be why? i dont think im pregnant due to the negative tests but is there a chance? im not trying to get pregnant or anything just hella confused on why i’ve missed a period for 2 months😂