Birth Control After Baby

Anastasia
I am wondering what different women are doing for birth control after the birth? 
We were using the rhythm method but apparently that doesn't work for us! 
I am a cancer survivor (Hodgkin's Lymphoma) and due to have radiation to my chest I already have a heightened chance of breast cancer so I am wary of taking a pill that also causes a risk of breast cancer. 
My ObGyn says there are less hormones involved in using the under the skin implant. Does anyone have good experience with this? 
I'd appreciate hearing any and all experiences related to birth control! Thanks 🙏🏻