After surviving Hurricane Katrina in New Orleans, we all have bug out bags. My husband and I split what is included. Naturally we have all the usual items, flashlight, water bottle, granola bars, bandages and OTC meds such as aspirin (really needed it during Katrina), extra socks and underwear, soap, small size shampoos, eye drops, tissues and a roll of T-P, and a number of personal items such as insurance paperwork. Also sunglasses, spare reading glasses, phone charger (hand crank kind), toothpaste and manual tooth brush, and a whole lot of other small items.
We were able to leave before the storm and stay with family for the storm. What we thought would be 3 days turned into 14 months. So don't count on your bug out to last for the duration. I find the easiest way to figure out what you'd need is put box on your counter in the bath and one in the kitchen. When you are getting ready in the morning, put each item you regularly use in the box. Then inventory after a few days. Whatever you needed at home, you're going to need if you have to evacuate.
Also, remember that ATMs didn't work for weeks and prescription drugs ran out the first week after the storm. Have extra cash and your meds for at least a month.
Keep an address book with the addresses, emails, mobile phone numbers etc. of everyone you will need to contact The landlines were down for a month in some areas but you could text from some locations. Also have old fashioned paper maps with routes marked to key meet up locations. Make a copy for everyone you will need to meet up with after the disaster.
Also, this is just a personal thing but I keep at least one pillowcase in the bag. Nothing like being able to sleep on a pillow that feels like home even in a shelter.
Good luck with your bag. We hadn't had a hurricane in 40 years until Katrina. Luckily we had family to rely on in the country when our home was wrecked. Not everyone was so lucky. Even 6 year later, there are still people living in cars, tents, and on friend's couches who used to be homeowners. Don't think it can't happen to you, because no one is immune from disaster.