I'm a bit worried for you.
You mention that having a couple of G&T's makes you "appear more intoxicated than you actually are" due to medication.
You also say that you only drink very heavily as long as there is another adult in the house.
You've mentioned multiple reports on you to safeguarding agencies.
You can't really "appear more intoxicated than you are", can you? You are however intoxicated you are. Just because you've had only a couple of drinks, does not mean you are not heavily intoxicated. The fact that your medication, which you are aware of, contributes to your intoxication, does not make you less so.
Your references to drinking heavily if someone else is home is worrying. I honestly don't think many people drink heavily for no reason.
You say you've had reports where the information is otherwise accurate (e.g., person reporting you knew you had another child with you). Yet you aren't sharing who even may have reported you. In such specific circumstances, you must know who is reporting you, based on the situation.
It sounds like there is a problem going on here. I wouldn't worry about proving whether what you're doing is "legal". If there are children at risk because of your behaviour, that's the problem.
It is okay to admit you need help, and services will work with you, not against you, to help you and your DC. I know it sounds really scary and you may think that admitting you are struggling with substance abuse would mean heavy involvement straight away, but it really doesn't.
It sounds like, reading between the lines, the best thing for you to do at this point would be to acknowledge that you understand why there would be concerns, and if it really is becoming a repeated issue, I agree to just stop drinking. Find another way to unwind, pamper yourself, whatever.