Struggling need a little advice

Hi everyone

Could someone advise me please im really struggling to keep up with simply piano app im now finished the essentials part 2 but im really struggling to read sheet music still and wondering if doing some reading would help I feel the simply app is very very light on the theory side of learning! Anyone else find this the case that have used simply piano app?

Would doing some reading of piano books actually help because at the minute im reading the notes by numbers more or less at the moment