I'm not on Topamax anymore (I experience to many terrible side effects), but I am 1 month away from giving birth.
I'm not going to lie, it's been a tough struggle for me. I've had a chronic headache with migraine for over 10 years and I was on a lot of medication including narcotics and I had to go down to almost nothing. My doctor prescribed to me Benadryl shots (which I've been on for years) and Percocet to take when it got really bad. My headaches have progressively gotten worse with the additional stresses that come with pregnancy. Therefore, my doctor is having me take oral magnesium as well as giving me magnesium shots. He's actually just written me a prescription for it, so my wife can give me the shots at home. I will tell you that the magnesium has been extremely helpful. I'm one of those people where you give a medication to 4 people, I would be the one where it doesn't work. However, the magnesium does work for me and I’m finding it helpful.
I would look into the magnesium and I wish you the best of luck!