I would recommend you to consult some professionals (on our forum) before purchasing the mouthpiece for the following 2 reasons:
1. they have some ideas which mouthpieces are suitable for your trumpet (by the way, what model of trumpet are you playing?); and
2. they might give you some suggestions on the size you choose (personally I don't recommend 1X or even bigger cup, if you have a good control I think 3 or 4 are the ideal size for most people, I use 1X equivalent because my lip is much bigger than regular)