Implantation cramping on one side of uterus?!

I am TTC and am 13DPO. On 11DPO I started feeling cramps and dull pain on what feels like one side of my uterus. I’ve been feeling them for 2 days now. Do implantation cramps only happen on the side of the uterus the egg implants on?

AF should start on 16DPO for me. I usually get cramps about 12 hours before it starts.

I’ve never felt period cramps like this, so it’s exciting if these are implantation cramps, but just want to be sure it’s okay if they’re just on one side! Also lower back pain on the same side.