I don't know you or your habits and can't tell you specifically what you should take with you, but I can suggest what I do when I travel or just have a multi-day event planned. I have a form that I created that lists every single thing for each day's activities. It's mostly for clothes, but I also fill in toiletry items and reading materials and vitamins, etc. From electronics to the clip or scrunchie that I'll use to put my hair up at night. In my mind, I go through my entire day and make note of EVERYTHING that I use. Sometimes I separate AM activities from PM activities. Some days have less structure. I write everything down and then determine where I have room to consolidate or even add a few items that I MIGHT want/need.
Having it all written out helps me to be clear about exactly what I need. For example, I wouldn't just write "make-up". I'd consider my absolute must-haves (foundation/concealer, blush, mascara, eyebrow pencil, lip gloss) and build from there. I haven't traveled overnight yet with my 3yo, but I would imagine that I'd think along the same lines for him--clothes, favorite toys (pick a number), vitamins, toothpaste, soap and other skincare, mix-and-match clothing with multiple changes per day, versatile hat/cap, sunglasses, prescriptions/allergy medication (Benadryl?).
I tend to forget things that I might overlook throughout my regular day, like the flats that I wear between my car and my office, as opposed to the high heels that actually match my outfit. Or the cough drops that I like to keep on hand JUST IN CASE my sinuses start acting up and I get a sore throat as a result. So I write it all down for the days/weeks/months leading up to my trip.
Good luck, and be safe!