First: This is not at all uncommon. Most students do not really like classical mechanics. I love it now, but until I was 25-26, I wanted more than anything else to do modern physics like Quantum, Quantum Field Theory, Quantum Chromodynamics, etc. This appreciation comes in time.
I see by your page, you are a young researcher. You mention that you forget all the formulas you learned. You may not have a guide to show you the way. A good guide can tell you, physics is not mainly memorizing formulas or equations. I see you have read some biographies. The reason Einstein is remembered, is surely not because he memorized more equations than Newton, or anyone else. Physics is a manner of thinking.
Textbooks are written for specific readers. The best indication of the readership the book is written for is found in the preface of the textbook. Often, after reading the preface, you can decide whether this is the best textbook for you. I find Kleppner/Kolenkow problems challenging but their treatment somewhat dry. If you use another introductory textbook, like Resnick /Halliday or Beiser, you find these authors introduce chapters with judo tosses, pictures of lightning, pictures of quasers, lasers, steam engines and the like. These are not idle illustration. These can be a reminder (especially to a young researcher), of why they are studying physics in the first place.
Top physics problem solvers learn a significant number of techniques, but learning them too soon is misguided. I feel, before college, it is more appropriate to develop your imagination. an experienced problem solver (in my 60's), I feel my technique is excellent, but my imagination could use a lot of work. In that respect, some other advise given about joining a rocket club, a science group, talking to a teacher is better for you at this time. Too many problems may constrain original thinking and increase shortsightedness.
