There is no spell to become a witch, not unless you count an initiation (which you can do yourself). You don’t need to be good at meditating to start off with (I garuntee you’ll get better over time) and I’ve known witches who go their whole magical careers without visiting the astral plane. I don’t know what books you’ve been reading. It’s not something you have to fight for, you just be. Yes, you need to learn a little (In fact, I garantee that you need to look into it a lot more before you actually do. It’s obvious that you need to look deeper into what practicing magic really is. Being a witch is not some glamorous thing like on charmed; it’s a religion and a lifestyle), but it’s not like there’s some huge wall that prevents you from using magic.
Just research more and then find something you think will suit you. People practice ritualistic magic, chaos, demonology, shammanism, ect. There’s tons to choose from. Witchcraft has a lot of rules. I personally dabble in as much as I can. It’s all a matter of what fits you.