no period after NuvaRing removal

I'm a 19 year old college student and was prescribed NuvaRing last September. My doctor told me that I could wear the ring for 4 weeks at a time and insert a new one immediately after taking out the old (thereby skipping my period). When school ended, I went off the ring around June 15 and began my period about 3 days later. It lasted an unusually long time for me, almost an entire week.

Anyways, I was going to go back up to school around July 17 to visit my boyfriend (who is up there doing summer research). I didn't want to get my period during that time, so I inserted a NuvaRing on July 11, pretty late at night (11:30pm or so). On the 17, we had sex twice, used a condom both times. On the 18th, we started having sex without condoms, including once in the day of the 18th and once in the evening. I went off the NuvaRing again when I came home, late on Monday the 21st.

Well, it's Friday morning now and my period is nowhere to be seen. My worry is that perhaps I did not wait the entire 7 days that it takes for NuvaRing to reach its maximum effectiveness... Inserted it on July 11 at 11pm, began having otherwise unprotected sex probably a full 12 hours shy of one week, in the morning of July 18.

I'm going to take a pregnancy test, obviously, but I'm a bit confused how to tell if this period is even missed, considering that I was messing with my cycle pretty heavy-handedly. My cycle off the meds is usually fairly irregular, my period coming 25-35 days apart. I have not had two full cycles in a row for a year now, so I don't know how my body usually would react coming off the NuvaRing.

I know there's a chance that I'm pregnant (condoms and hormones fail sometimes, unlucky me), so I will take a test. But I'm wondering how seriously having sex at 6 1/2 days of continuous NuvaRing wear instead of 7 might have impacted the effectiveness of the contraception. I also do not know how using NuvaRing in the admittedly irregular way I have been using it could impact the timing of when I should test in order to avoid false negatives. I'm under the impression that tests are most trustworthy after one's period is officially late (~5 days) or 9-15 days after ovulation. I don't know when my period (much less ovulation) should be, so I don't know if it's really late or not!

Anyways, if I'm pregnant, I'm likely only 7 or 8 days from conception. Should I hold off on the test or can I take one in the next day or two and get a fairly reliable answer? If I am pregnant, I will terminate (a decision I made before I started having sex), but this is complicated by the fact that I am going out of state for a month for an internship starting on August 10 and will not really have access to abortion services during that time. I'd like to avoid surgical abortion, so I'd like to know whether I'll need said services as soon as possible.

Sorry for this tome. Thanks for your help!