Quite a dedication 4 h a day... do you have a teacher? My best advice would be to find one as you may get all the help here but in little chunks and inconsistent order, even worse not understood.
Playing in the mornings is good as your brain is more open to everything. Now I fear that you may be a bit tense and stressed. Being relaxed and staying relaxed is essential to keep your mind and body open to learning.
As for exercises and pieces, it's good to feel that you are stuck and not making progress as this proves you have a sense of reflexion on your work. Take it slow, I mean very slow tempo on passages that are difficult. Make sure your hands are relaxed, shoulder and neck. Work slow, very slow until you feel the passage and only then increase the tempo. When you study a piece, rather than play it from the top, just jump on these sections that are hard, practice them slow and move on. When you feel you have nailed these sections after some days, then play the whole piece. That should be more gratifying.
Level wise: we are all different (mostly due to affinity with some material I guess and also understanding of music). Ring of the bells is a relatively easy piece in level 5 compared to others. And this is Delcamp's ranking (Trinity College system is different for example). I'd suggest you look at Tarrega's pieces in each Delcamp level and see which one you can play and cannot... that could give you (imho) a good idea.
Best of luck!
Field 2014, Oberg 2013, Vincente Sachis Badia 1977