Nuvaring backup method

Hi everyone,

I gave birth to my baby boy on Jan.9/08. I started Nuvaring almost 4 weeks ago now, and for the period between the birth of my little boy and during the first week of being on Nuvaring my husband and I were using condoms as our main form of birth control. During this time one condom broke DURING intercourse, which we noticed quickly and put a new one on immediately. Since starting Nuvaring (and waiting 10 days to have sex after starting it, as it says to have a backup method of birthcontrol during the first 7 days of using it) we have had unprotected sex twice. I am now on my "ring-free" week, and its been four days since removing the ring, and I have still not gotten my period. The box says that people usually get their period a day or two after removing the ring. I had not gotten my period before starting Nuvaring as I had been primarily breastfeeding my son, but have since switched to feeding him mainly formula as my breastmilk had been drying up significantly.

So here are my questions/concerns:

-When do you think the earliest could be that I could find out if I may be pregnant? Would the fact that I've been on Nuvaring for a month skew those results (false positive/negative?)
-What is the possiblility that I am pregnant? Could this just be a "skipped" period?
-What could the effects be if I dont get my period, continue using Nuvaring (ie inserting a new ring as I am "supposed" to 3 days from now) and I happen to be pregnant?
-Should I stop using Nuvaring completely until I get a period?

Thanks so much to everyone in advance for your help & kindness! I'd really apppreciate any info, especially if something similiar has happened to anyone else!