I'm 5'4 and weigh 184 lbs. Is it possible to have a Fat Transfer from my arms to buttocks? (photo)

Hello dear!
Thanks for the question and provided information as well.
Based on your pictures, you are a great candidate for liposuction with BBL, and I think you'll get very good results. 
Liposuction allows your plastic surgeon to transform your entire shape. You can improve your abdomen, back, arms and flanks, and of course your buttock, to give you a nice heart shape.
In general, you need to be physically healthy and at a stable weight, have realistic expectations, be a non-smoker and your BMI needs to be 30 or less.
l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

Unwanted fat from your arms can be transferred to your buttocks however it most likely is not enough to give you a noticeable new shape. Fat taken from the abdomen typically produces better results. 

Your arms can be used but they will likely not provide enough fat to give you a great buttock improvement.  Usually, the abdomen, sides, and back provide much more fat and can be used to increase the amount of fat transferred to the buttocks.Try to research this to find the surgeon who consistently produces the
results you would expect. Look at reviews on this site and see who gets the surgery right every time. Find
a board certified plastic surgeon who performs hundreds of Brazilian
buttlifts each year. Then look at the plastic surgeon's
website before and after photo galleries to get a sense of who can
deliver the results. Kenneth Hughes, MDLos Angeles, CA