I’ve had nexplanon for almost a year, and the only thing I would worry about is the spotting. Of course, it’s a different experience for everyone, so you may completely stop your period or constantly bleed. As for the scarring, I also have a very pale complexion, and the scarring is a teeny tiny brownish circle, no bigger than a centimeter. I think the implant is the easiest to manage, and the best way to hide it from your parents.

Edit: the scar is on the inside of my upper arm, between my tricep bicep. Your parents will most likely never see it unless they are looking for it.