I have run into this situation. And while 'I' and 'me' are more common, sometimes it is necessary in a recounted story to use the third person. (I can't seem to contrive an example right now, but I know I've run into this situation in the past.) If you are trying to be stealthy with the audience, then obviously use the pronouns of your current gender.
However, if the audience knows your background, there is no wrong answer. It is obviously appropriate to refer to yourself by your current pronouns because that's who you are and really were. On the other hand, it is not wrong to refer to yourself by the pronouns you used at the time, because that's what you used at the time.
No matter what you do, it's going to sound weird. Just carry on like you know what you are doing, and it will be fine.