Orthodontist says premolar extraction

Just to preface, I am 22 years old, and I’ve struggled with my self perception for a while. I recently got braces, and my ortho wants to go extract two premolars (which is set to happen pretty soon) from my top jaw because of overcrowding. I already have a pretty small mouth and a very large chin, both aspects of my appearance I struggle with, and I feel like getting these extractions will only make those issues worse. I really want a palate expander, and want to know if it’s even feasible/worth while at this point? I’ve brought up wanting to consider other options to my ortho, but he seemed less than receptive. How do I go about this? Do I even have other options? I really don’t know where to go for this