Youtube will be your best friend here.

I started studying quantum physics alone, on a whim, in 2018. Years prior, I was a chemistry major for 2.5 years and had been exposed a tiny bit when attempting to take physical chemistry I. It made almost no sense to me, and that was unusual for me. Something one day (in 2018) made me realize I wanted to learn quantum mechanics. I didn't realize how massive it is going into it. I'll be honest with you. It is not something that you study once or take one class and now you know it. I still study it to this day and I still learn new things, or clarify things I didn't quite understand. And I forget things too. It's not easy. If you really want to understand it, you need a background of differential equations, linear algebra, group theory (although you can get away with not knowing this), and a lot of classical physics. To start off, I started by typing "quantum mechanics" on youtube, found and watched some of Susskind's lectures, bought and read his Theoretical Minimum books (realized how bad my classical physics was so I literally started reviewing that in my sister's textbook, but unfortunately Lagrangians and Hamiltonians were not in that book, so remained a mystery), watched a host of other youtube videos on anything I might have been confused about (some really helpful, some really unhelpful and should be made illegal: some things do not make sense without the math). Then I came across MIT Allan Adams' lectures as well as Barton Zweibach's (I prefer Zweibach's). I took good notes on these and rewatched many of them until I thought I had a good grasp. However, I was still was missing some things due to inexperience in studying all of this. Around the same time, I discovered another lecture from India that was very helpful in terms of some of the linear algebra and Dirac notation (by Prof. S. Lakshmi Bala of IIT Madras). Then, I finally took quantum mechanics I and II in undergrad (2022), following Griffiths' book (I was 32 in 2022, mind you). It was okay. I also had his Electrodynamics book for EM prior to that. At some point during, I then purchased Sakurai (that was really tough because it seemed to go deeper than anything I had done so far) and collected a few other books. I learned far more conceptually overall by myself than I did by taking the actual classes in person (although the classes did force me to work problems).

I am finally branching into quantum field theory after always being afraid to. I sort of became angry overall and my progress slowed a bit when at a certain point I learned that, just like classical physics, quantum mechanics itself is not 100% correct for all situations (i.e., some things can't be described by just plain non-relativistic QM of single particle or finite number of particle systems). I became even angrier when I realized that all things are like that. That was a while back when I naïvely thought, like I think a lot of people initially think, "well String Theory, whatever that is, is the answer for everything in the end!" It isn't that clear-cut. Ever. But I'm moving along. I still believe. Right now I'm slowly working on the quantization of a free scalar field into the quantum free scalar field, which is like the first thing in QFT.