Passing a drug test - urine

So I have been clean about 18 days and my test is in the morning. It is a hospital lab test. I haven't been doing anything differently up until 3 days ago. I started eating lots of red meat. And I plan on drinking lots of water and Gatorade tomorrow morning starting 4 hrs before I go in. I was also gonna try some salt, maybe 2 tbsp (one at 2 hours before and one at 4 hours before). I know to take b2 also, but my problem is I accodentaly bought timed release ones. I'm wondering if I could take a bunch tonight and it still help by tomorrow morning. I'm thinking it probably won't help at all because they're released at a certain amount over a extended period of time. They're not the kind u can open so I don't know what to do. I'm worried they'll be suspicious of clear urine and then go on to test for everything else like creatinine, specific gravity, etc. also wondering if eating tbsp of salt will even help with specific gravity. I know that the more salt your body has the more water it holds on to, so what happens when you have a ton of water? I'm just confused at this point after reading so much trying to figure out how to pass. By the way, I'm female, about 115 lbs, 5'4", pretty high metabolism. I smoked daily for months and months and it was good weed. I just hope I pass and maybe somebody can clarify this atuff for me.