Serenity,
I took my test in June and I work for a hospital.... I was not observed but they sent me to a lab. I passed with QF and used dilution as backup. Remember the vitamin is used to color your urine, you don't need to be taking it beforehand. The B2 is used to color your urine vitamin yellow when you have drank so much liquid that your pee is clear. Let us know if the B12 does the same. If you are going to dilute, make sure to raise your creatinine level by taking a creatine supplement or eating a lot of red meat before your test. It takes a little while for the creatine supplement to manufacturer itself into creatinine, so it needs to be done at least a day in advance. Be careful with the niacin... there are mixed reviews about it and it can be dangerous or at least painful (it makes your whole body feel like its burning) if you take too much. If you have time (or cash) for a home test, you can see if you need to sub or not. Like killerweed said, you are a light smoker (or you have been in the past month) and you might be able to pass with your own. I wish you the best!