What can I do for the serotonin deficiency? What is best to do? Take tryptophan or take 5-HTP?

We want your tryptophan metabolites to be lower. We want them to be low on your Organic Acids Test. You actually want them to be low. 

Because tryptophan is the precursor to serotonin. And then serotonin is the precursor to melatonin. Serotonin is methylated to yield melatonin.  
Most people have high serotonin and low melatonin.  
And we want to increase the conversion of serotonin to melatonin. And we do that by improving methylation.  
If methylation is impaired, taking tryptophan or 5-HTP will just make you worse. It will just lead to the buildup of serotonin. 
So I don't recommend trying to increase serotonin. If you have impaired methylation, you don't want to be taking tryptophan or 5-HTP.  
We want to be increasing melatonin production. And we do that by optimizing methylation, and increasing the conversion of serotonin to melatonin.