200lbs at 5'8" would be your genetic limit if you were 5% bodyfat. It'seems okay that you're carrying bodyfat but consider:
Frank Zane competed at 185lbs contest condition 5'9", he used AAS.
CT is about your height, IDK his weight but it's >200lbs I think. He's 5'8".
Your genetic limit is kind of irrelevant. Are you looking for permission to use AAS from Internet strangers? You didn't list your lifts or post pics. Why? You're in the UK if you're talking about stone weight, AAS is kind of legal there.
Most sources say to not use AAS unless you're under say 15% bodyfat. Remember that every pound of fat means more aromatase enzyme converting your drugs to estrogen. Which means you need more AI.