Yes, I know exactly what you are talking about. I was diagnosed with hemiplegic migraines two years ago, when I was 29. I was at work and all of a sudden the entire right side of my body went paralyzed. I fell out of my chair and eventually was able to call somebody to my office for help. I was in and out of the hospital and had a battery of tests done. Like you, they initially said it was TIAs, but after everything came back clear they thought it could be a migraine disorder. I had never (and still have never) had a 'headache' migraine so the thought of this was very odd to me.
I was getting the episodes daily, where the right side of my body would go out for about 10 minutes. I had little notice. My 'notice' was that I could feel my cheek going numb and then within about a minute it was full-on. Then for about an hour afterwards my right side would be weak, but I could function. I was put on daily aspirin and topamax. That stopped them for a couple of weeks, but then they came back every day. I was definitely living in fear. I remember on one occasion I was giving a presentation to a group of doctors and I completely bombed. I was so nervous that I was going to have an attack in the middle of it that I could hardly talk.
I ended up seeing a neurologist who specializes in migraines for my official diagnosis. She said it was classic hemiplegic migraines. She took me off the topamax and started me on verapamil, which is a calcium channel blocker used to commonly treat high blood pressure. I can't speak highly enough about that drug. Since the day I started that, almost two years ago, I have not had ONE episode of full paralysis. Now I do occasionally get episodes, but they are so incredibly mild that all it is is some slight numbness in my cheek and a bit of weakness in my right arm. I can completely function through them and nobody would ever know I was having one.
Since starting that I no longer worry about having attacks. I have also made a slight adjustment to my diet because I noticed caffeine would often trigger an attack. As a result, I no longer drink anything with caffeine in it.
I would recommend either seeking a migraine specialist and seeing what kind of other preventative you can go on (like verapamil, but stay away from triptans) or asking your primary care physician about starting you on something.
Good luck, I know it's incredibly frustrating and scary.