No period in 4 months...

Hey guys i’m on lo loestrin Fe and i’ve been taking ny pulls a few hours late/ forgetting to take them and my periods have become rly irregular— like i haven’t had one since October! I’ve had sex twice ( once in october before my period we used a condom) and then again like 2 weeks ago ( also used condom). Ive been on the pill since may.. i’ve lost weight since then ( about 7-10 lbs) and i dont feel any nausea or other common pregnancy symptoms.. is this normal? What might be the cause?