hello girls, quick question!

i know the chances of getting pregnant after giving birth are super big but i just got my first period this last week and i’m calling my doctor today to get an appointment for my birth control. i just wanted to know, can i still be pregnant even if i got it? my boyfriend and i have been having sex before my first period (i know i shouldn’t have but i’m super horny lately 🤷🏼‍♀️). i’ve been having mild to really light menstrual cramping, nausea that comes and goes and i’ve been feeling some types of “changes” right where my baby was at... i just want to know if i’m overreacting or if there’s possibilities. my son is a month and 24 days.