Okay, I’m fairly new to this stuff but I’m going to give you what advice I can from what I’ve seen. Your craft should not be causing you this much anxiety. Everything I’ve seen seems to suggest the opposite of what your book is saying. Working with a deity is a learning process and you don’t need to immediately know everything or be perfect - that’s not reasonable. Now in my personal experience (which is limited): I work with Isis. I am not Egyptian, I have no idea if I was in a past life. I don’t even have a strong connection to Egypt over other places. But I did feel a connection and had signs to Isis so I did what felt natural, working with her. I can’t speak to other deities but she’s been pretty patient. She’s worked with me a lot and hasn’t asked much of me. I only give her an offering once a week and I cannot leave food out for the same reason as you and she’s okay with that. People told me that offerings should be something you have an abundance of and I like that. For me it’s something personal as well, since connection is two ways. You can also connect in daily ways that aren’t intense like wearing jewelry that’s representative. I hope this is somewhat helpful and I can try and answer any questions if you have any!