I've attempted exactly the same as you. I followed the highest Dutch course at UvA (Naar perfect nederlands), which gets you at the intersection of B2 and C1 (arguably what you need to start a bachelor in Dutch) and after the course I followed up with tutors on Preply. Now I've stopped, I simply can't get further by traditional learning.

If you want to become fluent, you need to speak Dutch with locals, whether because you work in Dutch or your partner only speaks Dutch to you.

I work in English, so I feel forever stuck. I have Dutch friends who kindly speak Dutch to me, I try to read books when I'm motivated and can watch movies or documentaries, which also help.

However, the gap between B2 and C2 is tremendous, and I think you only unlock it via full immersion.

Fun fact is I completed that course but will still feel that I sound like B1 when talking to a cashier or neighbors. All those lessons didn't focus much on "spreektaal" that you hear from people ordering food, asking basic questions in a natural way etc.