as you in the asylum process here, it would be the easiest to marry in Germany. because you will not be allowed to go to Canada easily. So your girlfriend needs to come to Germany for marriage.
Further, to have a realistic chance that your marriage will be accepted by German authorities (e.g. not a fake marriage) you actually should move together. Otherwise it will be difficult to get married in your situation now.
You could also try to marry in a another EU Country such as Denmark and then get that marriage approved in Germany.