Concern about najis ( period)

Hello everyone I'm subha I'm 15 yr old and i worried about my najasa well I think if I take bathe or wash vaginal area during period and and my pad with period on it would spread najis like how I'm supposed to clean it Doe's it spread najis or not aksed ai totally confused me if wear pad with period on it while my leg and vagina is wet so my leg also became najis how I'm supposed walk all over the House I can't change pad frequently right please help me