Unsure?

So I'm on the pill and I missed one a few weeks ago. My boyfriend and I had unprotected sex a couple days after (it was a Sunday morning) and he came inside of me. We got plan b but not until Monday afternoon around 4 so the effectiveness decreased I'm assuming? Anyway, we were having sex two days ago and on the bathroom sink where i was sitting there was like really light pink discharge. I've felt nauseous a couple mornings but maybe it's in my head... also my boobs have been pretty sore so I'm just wondering if I should take a test? I'm just so scared and we're not in a good spot financially for a baby at all right now