Thanks for the help everybody, this problem is solved!!
A buddy of mine came over and taught me how to correctly measure the voltage and amps used by this led.
It turns out all of my theories were wrong (which I could have known) and the solution was very simple.
The first measurement I took showed me that the 12v adapter I was using really outputted 18v. The thing is really old and I should have never even used it.
My friend immediately knew that this was the culprit and upon further inspection we noticed that the 20 strand strip also had the same color problems, just hardly visible.
I have another beasty PSU that I am using to power my ambilights (LPD6803) that supplies 12v 5A, when I measured that the multimeter gave the exact 12v result and the problem was solved.
One of the mistakes I made was thinking I needed to supply less amps for less leds but that doesn't make sense at all. A shorter strand just draws lesser amps right?
Sorry but I am just a Arduino beginner that wanted to program some leds with c++.
Now I'm back to what I am good at .. writing code ..
(does anybody what to see my project, do you have showcase forums for that?)