welcome to the board - very mature for 19.
in short, optimal levels are 500-827. At worst you are low-normal and changes in diet/ general nutrition at 19 will do wonders. read the following and also get your 'free testosterone' level check if you are still concerned.
Some men have their total testosterone measured. Standard reference ranges are between 241-827 nanograms/dL for most laboratories. Many older men are below 241. Optimal levels of total testosterone for most men are between 500-827 nanograms/dL. If your levels are lower than 500 nanograms/dL or even a little higher and you still have symptoms, you should check your free testosterone by the Direct (RIA) method.
lots of good information here: http://www.lef.org/protocols/prtcl-130c.shtml#total