What Size Board should I skate?

I'm about 5 feet tall, with a size 8 shoe. I currently have a 7.775ish board. What size skateboard should I be using? I'm thinking of going smaller and using 7.5. I can ollie and pop shuv-it on a 7.8 but can't kickflip. Will it help if I go smaller to 7.5 or what size? I'm in this for tricks. Also I mgiht need the size for other parts like wheels too plz. Wheels I don't care much about. But I want ones that are pretty fast.