Implantation Bleeding? FYI some TMI!!!

Emily

So my period is well overdue. I took an at home test when it was 8 days late and got a negative. My husband and I have since had sex. Ten days after having sex I noticed a small amount of dark/brownish blood in mucus(?) when I wiped. I assumed I was getting my period even though I have never quite had spotting like that. The next day there was no blood and everything was basically normal except for a little more mucus (discharge?) than usual. Today is the second day after and still no period and no more spotting. My period has been irregular in the past but the last 4 months or so it’s been on point. Could my calculations on ovulation and all that have been off? Could that have been been implantation bleeding? If so how long before I try another test? Sorry for the long post, we are trying for our first child and I am new to all of this. Please any info, input or insight will help and will be greatly appreciated.