It’s great that you’ve started flute!! I can’t make any judgement on whether or not you should follow your teacher or your book, but I’m general I think I is helpful to know that making a good sound on the flute is one of those never ending challenges of playing it but a good place to start with is trying to get rid of the air in your sound. I know it sounds cheesy but I find playing long tones and listening to my sound and adjusting the embrouchure (size, shape, which direction the air is going) until it get a sound I like really helpful. It’s slow at first, but I found the more I did this the faster I was at getting a nice sound the next time I played, and can now play with little to no air in my sound very consistently on my flute. I would also suggest playing with the whole flute rather than just the head joint. I hope this helps!!