Need help with AC wiring.

[AlumaLite]

I got it all in and working , but in reviewing my work I am confused on what to do. I have my box with a 15 breaker and a 20 amp breaker. My fridge and one outlet under the table is the only thing off of my 20 amp breaker. My 15amp breaker is for my other outlets and converter. I was plugging my AC into the outlet under the table which is the 20 amp but didnt realize the Fridge is on that too. I also found out the manufacturer says to use 12/3 which I used to the plug, but from the box to the outlet is 14/3. I called 2 local dealers and they said for the small 2 feet of 14/3 line used, it will hold up. They said basically it'll hold up to about 20 amps. But what I am concerned about now is operation of AC and fridge. Do I always have to run the fridge on LP now? Can I run a 120 stand alone 20 amp fuse inline with the black wire right to the 3 connection poles in the box?

Alumalite