I have not even considered a steriod till now and was wondering if this is right

I have been working out for 2 years and gained 30 lbs without the use of any steroid. I weigh 175 and can press 265 2 times. But i have not gained or increased size in the last couple of months and am considering starting a cycle. I have a 10 week cyle of deca and the provider said use 100ml a week. Is this correct or should i use it more often. I eat as much as I can. I wish to now a little more about my circumstance and if i should proceed. See, i have a good figure, but i am not as thick and muscular as I wish. People say i look big, but when i look at myself in a reflection i see diffrent. Please help with some helpful hints. Thank you!