Dark brown discharge ? TMI

Took 2 PT a first response and an .88 cents Walmart brand , on Tuesday morning 6/9 and another on Thursday morning 6/11 clear blue , got BFP. Tonight 6/11 I saw dark brown spotting . Is it normal , like , old blood leaving body, implantation bleeding. I have no cramps or pain at all anywhere near the “normal” areas I will usually get when AF will arrive . I supposed to get my period Tuesday the 9th , and I am regular and have not got it yet .I do have Breast and nipples are extremely sore feel heavy , and feel on and off like being poke with a needle or pinched very quickly . I got a little nervous because we are actually excited with the positives test of our first one 🥰

Thank you .