Help!!

So first of all I want to say I don’t want to be pregnant at all as in avoiding it at all costs.

Anyway I have been taking the pill for about 3 months now and because of this I haven’t had my period they said it was a side effect. I had sex yesterday and the day before my boyfriend was wearing a condom and I had taken the pill however he had come inside me but we checked the condom no rips nothing like we checked and we were okay and I went toilet straight after (I have suffered with cystitis a lot because of forgetting)

But when we had finished and I got off I noticed a little blood on the base of his shaft and noticed that today I was bleeding a little bit. I was speaking with my sister and she said as long as you’re taking your pill I wouldn’t worry. But could this be implantation bleeding??