Implantation bleeding?

I am almost 11 weeks postpartum and have not had a period yet but on Sunday the 25th in the evening when I went to the restroom I noticed there was some light pink spotting on the toilet paper. I thought I could be getting my period so I put on a pad and wore it for probably 2 hours and there was barely any spotting I took it off and I haven't had any spotting since then.

I'm a little nervous that it could have been implantation bleeding we do not want any more kids so I hope it was nothing but I will take a pregnancy test in about a week. My husband got a vasectomy but it's still not effective for another few weeks and we have be intimate. We had sex on Friday the 16th and Monday the 19th which could make the spotting implantation. Does this sound like implantation bleeding?