worried

on dec, i had my period on dec 1. but it was vvv light. then on dec 21, i had another period and its heavier this time. (i was still a virgin during this time) the whole month of jan i didnt have my period. so on jan 26th i had unprotected sex with my boyfriend. he cum outside (we did it twice). now, i’ve been reading reports that you can get pregnant from pre cum. now im really worried bc im only 15! i know i shouldnt be having sex, i only got curious. would not do it again w or without protection! moreover, just this morning (feb 4) i started having vvv light blood, now im not sure if this is implantation bleeding or my period bc its so light! so, do you think im pregnant? and if so, when can i take a test? is it too early to take a test tomorrow morning? thanks in advance! hope you can help me with my dilemma. i also might not be getting my period due to medications that i took last month for my stomach flu, and i have been so stressed last month and anxious that i might be pregnant so that may be the cause? or am i pregant? thanks!