Its because you do not have a testosterone base.
There is a reason just about ALL VET's say NEVER run oral only cycles or testless cycles.
You will be shut down and not have test in your blood, other steroids are not used in the exact same way as test would and its needed by the body for many functions.
On this forum alot of supp places push oral cycles, even as an LG rep I dont and wont.
When I say TEST BASE, it does NOT have to be injections, though I feel those are most optimal. It could even be a test cream, even dhea and/or pregnenolone.
you are also a bit young, your not done developing (most of it anywy) till around age 23-25.
also if this is your first cycle you may be expecting things srom steroids that they are not.
also you can take all the aas in the world and not gain much of anything without the right diet and training.
I know a guy that used same lab and did same cycle as me (teste, deca, dbol) but went a bit longer and also added winny. after 4 months guess what? I saw him (not a close friend so i didnt see him in a while) and he looked liek eh never worked out still, all he got was a fat face and actually looked WORSE then before cycle. then he askes ME WTF I am takign because I am huge. *i should note i told him time and tiem again you need ot eat alot of protein and work out right, because I could tell when i said this he quicly agreed and brushed it off. he thought steroid where special.
i guess due to media and people that actually know how to eat and lift he thought steorids it self would do the trick to soem mass..... not the case. and even with steroids expect YEARS of use and lifting to gain any worthy mass. its not as easy as some think, just because you are taking steroids...
GOOD LUCK !