Test Question HELP PLEASE!

I took a pre-employment urine test through a local lab about 2 weeks ago for a college program I have been accepted into. It was a 9 panel with a 50ng/ml cutoff I believe.

It was random but I had an inkling it might be coming so I really hadn't been smoking much for the months leading up to it. Roughly 2-5 pipe hits a week for a few weeks leading up to it. I was able to get an OMNI cleansing drink and followed the instructions and got a negative home test about 40 min after drinking it. I had also already had about 1 quart of water that day - which is normal for me, I drink A LOT of water. The next morning I also got a negative result on a home test.

I got a phone call yesterday from my school saying my test was too diluted (not really a surprise there) and I needed to go to the MRO's office ASAP to retest. I have not smoked since June 21. 5'4" 133 lbs, pretty active (biking, walking weekly some hiking on the weekends). I took another "1 step detect" home test with the tail end of my first void of the morning (I was really tired and forgot I needed to take it) and got a negative.

My question is, should I put the test off a few more days or just get it over with? ALSO, how much water should I drink? I am not going to follow the dilution sticky, if I get another diluted sample it's a guaranteed fail and I really think I'm clean.

Any advice is appreciated!