I'll be honest. That sounds like it's going to lead to horrific results, if you're not developed yet in any shape of form. I don't think it would be healthy, and no sane doctor should that. That's like women who inject cement into their buttocks trying to look like Nicki Minaj, but end up in a monstrous results....
You need a foundation to build a house. (I am assuming you're not on hormones, no breast development, because you said you can't transition for a few months; which is different from going full time in my opinion).
What if it flips on you because there is nothing to keep it there... It sounds like that implant can rotate and move because there's no fatty tissue to grab of hold of it. What if you slept rough toss and turn, and push that implant down the side of your rib cage....
No! Don't do it!