Hi there,
I'll suggest that you be very honest with your doctor about the situation with your parents. They might just be able to give you some nice ideas on how to deal with the situation.
I've read regarding your parents's beliefs towards your mental health in many of your posts. I don't know if you've tried this before but have you ever done something like, ask your counsellor or doctor to explain the situation to them? Maybe let the therapist know about it and ask if they'd be willing to speak to your parents and try and convince them that none of this is for gaining attention and explain the benefits of medicines Because of course, having to hide it from them is a chore and their support will be very helpful on any day, right?
You can also take your general physician's help with this. Speak to them beforehand, find out about their point of view regarding mental health and medicines. I think they might be trained in your country regarding the basics of the benefits of medicine with mental health disorders. If your parents trust this doctor, speaking to him/her might have more convincing power than speaking to a new person.
If you are able to hide the medicines from your parents, could you stock up on them before you go home? If not, then you can simply work on your fitness and go out for regular walks.
As for what to ask when getting prescribed, personally I spoke about things like how I am a very busy student and can't afford to take medicines that make me sleepy.
And how I am all worried about my weight and won't appreciate meds that make me gain it.
Apart from that, I had trouble keeping up with the schedule of taking my meds regularly when prescribed for twice a day. So we had worked out a schedule wherein I had to take them only once a day.
Ask whatever comes to your mind in the first visit, and for the rest, give it till the next visit. You'll find out about your concerns by subsequent visits.
All the best!