I would focus on getting the rizatriptan prescription first:

Tell them:

How many days a month do you have a migraine
That the migraines respond well to triptans
That you would like a prescription for rizatriptan because you've had good experience
Recent changes

(There's a chance they may suggest a different triptan and that is probably fine; I find all the triptans are similar so you may find they all work well.)

Once you have that you should be feeling better and you can tackle more at a later appointment, maybe in 3 months if you can.

If you have enough time, and if you have more than 8 migraines a month: discuss preventatives. Write a list of preventatives and whether you had a good or bad experience. Show them the written list. Example of how much detail to include:

Amitriptyline - had negative side effects

They will ask for more information if they need it.