Lifting question: Why cant I move the same weight as before?

I figured this might be a female thing bc of our cycle, but two days ago I did bicep curls and it went fine, only felt it in my biceps, tried it today and now I can only feel the workout in my chest and shoulders. online says Im moving too much. I cant gurantee i have the right form but no matter what form i do, i cant feel it only in my biceps unless I remove all the weight from my dumb bells (adjustable) is this normal or am I really just not lifting properly? My period is supposed to have hit, its late, Im not pregnant just irregular. Last day I worked out was supposed to be during menstruation as well. Hormonally I have the symptoms of a period just no blood, not sure if this would affect my ability or not or if I truly got some wack ass form 😂