Are you asking is it normal? I think it is. I am also suffering more than 25 years now... in my experience not just the frequency but the type of migraine pain is changing. (I am 49 in two days) It started about once a months with huge head pains on the left side in a line that I could almost draw. I also had heavy vomiting for a day or so.  

While I tried several preventative meds I controlled the episodes quite well with caffergot suppository. However became more frequent. (2 weekly or weekly) In this process seemed like the pain location changed as well. It was sore ewerywhere- temporal, my eyes and the tope of my head too. I learnt about the rebound effect. At this point I had one "clear day" a week, (when I did not feel it is coming or did not recover from it).  Started accupuncture and not using caffergot, the only thing that helped was a big thing.  (I virtually have no medicine to control the episodes since). The next change is the menopause I was quite young for it but I had the first symptoms when I was 40. Although episodes were frequent but somewhat more regular and bearable. Head pain was more frontal and temporal. However it was frightening to experience vertigo, forgetfulness, mixing words as a new symptom,  and increased feeling of tiredness.

I am at post menopause quite sometime and for me the miracle did not happened. I have a lot of pain and vomiting still and the head pain starts from the neck and moves around.

However I heard a lot of good stories when the Migraine just stopped... especially with women after menopause.

So do you have big ones nowadays? Probably it is frightening ti\o experience speech and tiredness but  I think these will settle , at least it did for me... or just got used to the fact that I am getting old??? But I don't give up hope to get rid of the whole migraine thing yet.