Hi Tricia
Sounds like you're almost doing the right thing
so only minor adjustments and you can look forward to a happier time in the last 6 to 8 miles.
I trust you have a good pre marathon taper so eating normally up to the wednesday before the marathon is fine.
Thursday have a couple of small snacks through the day on top of normal meals
Friday... this is THE most important day for food and sleep. Friday evening is your marathon meal... eat as much carbohydrate as you can. The aim at the end of the meal is to feel very full... this is the store that will help you in the marathon. So dinner and pudding! Enjoy!
Also, obviously plenty of hydration.
Sleep is most important on Friday night as well so get a good 8 to 10 hours.
Saturday the only aim for this day is to not get hungry. Any big meal will not really help you in the marathon because the body hasn't got enough time to process it. So lots of carb snacks and maybe a small meal in the evening... just don't get hungry or thirsty.
Rest from about 4pm Saturday afternoon... and that means feet up complete rest in your hotel room, watch the tv, get your kit ready, but that's about as active as you should be.
If you don't sleep too well on the night before you don't need to worry. You've got the sleep in the bank, you're loaded up and you're rested.
Marathon Day follow your usual breakfast routine. Stay as calm and confident as you can so you don't waste nervous energy. Gels... sounds like you have that sorted too, I take them every 5 miles but the important thing is to stay ahead of the energy rather than have to play catch up. I usually take 5 SiS gels with me... 4 normal and 1 caffeine. The caffeine one is the last one I take and it gives you a kick just when you need it 
Anything else I can help you with... just ask 
I am the one-person cheerleading team after all!