Confused big time 😳

So I have the nexplanon and usually it’s been a little funky before my period would start blood would be deal brown for days n suddenly appear bloody red the back to the dark brown and then go away but this most recent time he appeared tan then bright red then I had sex and went away this is by far the shortest period I’ve ever had on the nexplanon I only had it for 3 days wierd thing is I’ve noticed this happened a whole week ago but I’ve started seeing my boobs get bigger n I though it was cause I been working out until I realized I haven’t been working out my chest like that and I usually get bigger boobs and my boobs get even when I get pregnant because I have two different cupped boobs well that’s what’s happening and the most recent time I found out I was pregnant this happens I found I was pregnant in less than a month because I’ve noticed these signs but I’m hoping it’s nothin considering I have the nexplanon but I know I can be very fertile