You are doing everything right. No need to question yourself. The problem is not your attitude towards knowledge and problems but the general laziness of the todays research approach in physics. Most papers are plain bad and/or wrong due to the high stress researchers feel to publish and show "results" of their work. If you struggle to read to the end of any paper, that's probably not your fault. Currently, there is no major spirit in the physical community to "work up from scratch". It's accepted to continue from some high level statements that are not very well understood. Fundamental understanding has never emerged from such doing and that's probably why most (theoretical) research is rather "technical" today, e.g. calculating some minimal corrections to cross-sections. Although, this level of extreme specialisation has been very important for large-scale experiments due to the need to manage the huge workload, it sometimes lacks the aspect of creativity. This is ultimately boring for someone like you, that seems to strive to understand everything in detail. I advise you not to stop on that approach and to keep being passionate about physics. Sooner or later your fundamental understanding will give you a lead.