Advice on driving school

Hello to each other, I need your help with a driving school problem. At the moment I’m doing the motorcycle driver’s license. Unfortunately I’m rather small (Vietnamnese). At the registration I had also asked about the size, but I was assured that it is possible to ride on the open motorcycle without any problems. Funtkionet but not. I did a few hours on the throttled machine, but so I can’t get any further. The driving instructor suggested to me either to do A2 n and then in two years again a test (doesn’t solve my problem, since I’m not bigger in two years), or to buy my own motorcycle. Proposal from the instructor was ER-6. Now I’m thinking about whether it’s better to change the driving school, to a driving school that itself has ER-6. If I buy my own ER-6 now and sell it again after I made the driver’s license, I also put a few 100 euros in the sand. What would you do in my place? ? Does one of you have another suitable motorcycle? At Cycle-ergo I have tried a lot already, but most of the chopper-like ones don’t have 68 HP, which I need and should be bad for the slalom tasks.