Hi there,
Welcome to the forum. We do have members who are more versed with the migraine meds and hopefully they can shed some light on that. That said, I sure do feel if you are indeed being shrugged off by your doctor when you bring up problem symptoms you should (if you can) move on to a new doctor.
In regards to worrying about MS, please know I am so sorry your Mom suffered with hers. And, I'm very sorry for your loss.
Be rest assured there are good meds out there today to fight disease progression, and minimize attacks. Also, your increased risk of developing MS as a child of an MSer is small. This discussion will shed some light on that for you.
http://www.medhelp.org/posts/Multiple-Sclerosis/Genetically-Predisposed/show/1302989
If you can get to another doctor, it's best to describe your symptoms and your history. Let the doctor ask about mom and dad, siblings etc. Your fears are understandable since you lived alongside this disease - but no one is exactly alike, the disease is so varied from person to person, and if you do end up with it - you are young and you can fair very well.
Thank you for joining us, and I hope we can help put your mind at ease and be a sense of support to you.
-Shell