I'm confused.
First you said that if your dad stopped giving you money you'd be out on the streets.
Then you say his money doesn't even cover your rent & utilities. So which is it.

You said you used drugs typically once a month or less. Then you said twice a year.
So as a parent I see some discrepancies here. Maybe your dad does too.
First you told your dad everything....then you pulled away & told him it's not his business. As a parent this might be a red warning flag. He's worried.

If you're feeling guilty over lying to your dad about ur drug use then abstain from it till you finish your masters, get a job & tell your dad you don't need his money anymore.
If you have serious MH issues in CA talk to a dr & ask what you qualify for in using cannibis medicinally.
Or....just lie to your dad. We all lie. It's an option.
Or you tell your dad about your drug use & be honest. You enjoy it, it helps & if he wants to judge you about it...well your an adult now & it's painful. You'll get thru it. You're looking for validation from someone else. You need to find your own validation.

I think when I was close to 40yrs old I started to realize I needed to get the voices of my parents out of my head. Yes they are our lifetime teachers, but you need to take the reigns of your life soon. You'll make decisions that may hurt others in the process, but that's life. The good & the bad.
Are you ready for that?

Don't lose ur relationship with your dad over it.