You said you went to a part 141 school for your private pilot training, and it sounds like you are doing your instrument under part 61.
If this is the case, you are experiencing one of the major differences between the two types of flight schools. Most part 61 programs are significantly less structured than 141 programs.
At the very least, your instructor should have a syllabus (although many CFI's do not) which will act as a guide through your training.
As far as the books go, ask your CFII about any specific books that he/she recommends, but I would suggest the following:
Hope this helps!