So did you have your phone out or not? Your story is not clear. From now on, don't take your phone into the exam room at all, right? Then you can't be accused of having it out.
The first thing you need to do is to make sure that you have done everything possible under your school's procedures to make your position the best possible. That means you have an extra course, in which you need to get an A, in your school's policies and procedures regarding academic dishonesty, including whether there is the opportunity to appeal if you have a good enough case, and making sure whether or not those procedures have been properly applied to you. Is there an academic adviser or student organisation that can help? You can consult a lawyer without having them formally involved in any school procedures if there is a possibility of that hardening attitudes against you.
Your statement that the mark can be removed after a year of good conduct makes me wonder whether it is some kind of preliminary judgement rather than a final one? There may be some nuance there which could help you. For med school academic dishonesty is a very serious problem, but different schools may have different rules about what needs to be disclosed in which case what is on your record will be critical. Also, the more time between the incident and any application the better: if you can prove your good character with some years of seriously good work since the incident that can only help, so thinking about proving your abilities and character through a few years of an alternative career before applying to med school as a no-trad might be a good idea.
You do have a future still. It might be a good thing for you to talk to a welfare officer to help you deal with what is a difficult time.
