Its The usual, I'm to impatient to wait sort of attitude But what you should read is this thread.
http://forums.steroid.com/educationa...-per-cycle.htm
I personally would wait until I were 100kg to 105 kg natty less than 10% Body fat natty before considering a cycle, this is what you should aim for at your height.
Your experience of 2 years gym time is immature and any gains made on AAS will likely disappear.
If you jump on cycle now at 90kg you will blow up to around 100kg maybe 105kg but then when your off you won't even be able to maintain 100kg. Then you will have to cycle on again to reach that 100kg weight then so on and so forth.
This is all irrespective of your age ATM. That is a whole new ball game.
Get your blood work done pre cycle, this you must do regardless of age, inspect your natty test levels and ensure that you follow proper protocols and correct PTC to recover your system.
Even if you do every thing you are supposed to do, at 20 you may never recover, because you have not reached maturity.
But at the end of the day it is your choice, if you do choose this route NOW, get bloods pre, intra and post pct. also log your results wherever, and if by the likely chance you do destroy yourself and are stuck on TRT please use your experience to warn others of not wiring your due diligence.
But regardless of your age my opinion still stands that you are not even big enough for your frame natty or enough gym time to maintain what you may get on a cycle.
Post up you diet and training regime in the appropriate sections, and you will be surprised at what you may be missing that you need to improve your size natty.
Also test costs money but right now you are producing the most you could ever produce in your life for free, you would be short changing your self some $$$.