falling behind in my passions and life in general

I thought I'd have my life together once I graduated high school, but haha...

I manage to either leave week-long projects till the last night, or I accept the penalty of mark deduction anytime (most of the time) I submit past the due date.

I genuinely don't know how to combat this. I always tell myself to come up with a schedule whenever I have a free period, but even when I do, I never stick to it.

I'm currently studying Design, which is what I've always wanted to do and never thought I'd be able to, and yet here we are, but I still find myself being unable to do any of my class assignments on time. Every elective and compulsory class has everything I've ever wanted to learn, and I still manage to disappoint myself.

I'm currently prescribed Ritalin and only take half the tablet because the full tablet gives me immense anxiety symptoms.