Your MA looks great!! My needle size is based on the weight of my thread.....If I use just regular cotton, I'll use anywhere from a Size 10-12 needle, or if I use a heavier weight thread like 12wt, I'll use an embroidery needle....It's just so much fun playing with the different weights, textures of threads when doing machine applique....

It will probably be okay, but I rarely use a needle bigger than a 12, so I would say, try a smaller needle. You're doing a great job though.