Although shaving regularly (and back hair) can be a indicators of high testosterone levels, the lack there of is NOT an indicator of low testosterone. Whoever told you this was giving you poor advice. Going on clomid will do nothing but you make you emotional. If you really wanted to slightly raise your test levels, I have read some reports of people taking nolva and it slightly raising test levels without an anobolic cycle. But in my opinion it is hardly worth it.
Your problem is probably that you are not eating enough calories. Most 19 year olds have a very
fast metabolism, but don't worry. Over the next 2 or 3 years it will begin to slow down, and
gaining weight will become much easier.
Keep training, keep eating, keep learning. These things take time. You can not develop 30 pounds of muscle mass overnight!