Could I Be Pregnant When I Have Cramps, Nipple Changes, And Shortness Of Breath After Intercourse Three Weeks Back?

Hi! I m eighteen years old and idiotically had unprotected sex about three weeks ago. My nipples are slightly larger and darker, I have occasional cramps in my uterus-- I have a slippery slightly milky discharge. Shortness of breath which I didn t have. Like I ll walk up the stairs or just a short distance and it s like I m wheezing but I m not and it stops fairly quickly after I sit down. Obviously I ve been worried about this but I figured it d be best to use something like this before going in person for just fear/anxiety of it. I took two pregnancy tests eight days post intercourse and both came out negative-- then again it was eight days. I m also hungrier but I am a foodie so... thank you.