Again, I have not read Gallian myself, but judging from the reviews:
it seems like a bad book. It sounds very watered down to me, from reading the reviews, and it is very unusual for students to say a book is not advanced enough. Also the book is hideously expensive, and on that basis alone I probably would not recommend it, even if it was a good book.
Look, you don't need a "algebra for dummies" book to get started in algebra. After Apostol you should be well enough prepared to do Herstein or Artin. Those two books are the standard textbooks for undergrad algebra, you can't go wrong with them (chose one or the other). Another common undergrad book is Dummit and Foote, but again I haven't read that one. Chose one book (or two if you want) from Herstein, Artin, Dummit & Foote, whichever you can find for the cheapest price, and work through it , working on the problems as well, and you'll be more than fine.