Should I consider a pregnancy test?

[Lucafira]

I'm 28 and have been on Seasonique for about 2 years. My pack has only two and a half weeks left before my period is expected and I haven't missed any pills so far. Last two intercourse dates were Tuesday (11/15) and before that was 11/1; I keep very accurate track of these dates. After intercourse on Tuesday, I began seeing pinkish bleeding with a little tinge of brown - it's not even one pad worth a day and happened on Wednesday and today as well.

Yesterday I was beginning to feel more fatigued than normal and it has worsened today, to the point that I feel like all I want to do is hibernate. My lower back has begun to ache and I've been experiencing very mild, almost period-like cramps throughout the day. My stomach has felt more "bubbly" (acidic) than normal and eating anything is making me become slightly queasy. My boyfriend made mention today that I have been "extremely over-sensitive for some reason and it's making it hard for [him] to try to talk to [me] about anything;" seems I've been far more touchy than I realized.

I've never experienced full-on period-like symptoms like this nearly three weeks before my expected cycle arrival and have been pondering if I should get a pregnancy test. I have never been pregnant before and all intercourse between my boyfriend and I is unprotected. I've been doing a lot of "nesting" over the last week - cleaning like crazy, overly excited about plants growing, very motherly over a recent addition of three kittens. Only other thing that's different is that I had a 10-day course of Amoxicillin for strep throat last week and the last dose of that was taken Saturday. Am I just having some sort of pre-cycle condition, or is my anxiety about being pregnant justified?