I am prone to migraines as well and I am still nursing my 2 year old. Many women develop this conditon after pregnancy (even women who do not breastfeed!). When I am premenstral, I am very prone to a migraine. It's a combination of hormones and triggers.
You have to figure out what your triggers are and avoid them. For example, dh and are were fond of ordering chinese food once or twice a month. Well, within 24 hours, I often had a migraine - dizzy, excruciating pain, black spots, vomitting. Although the restaurant claimed that they did not use MSG... I am sure they were. And, MSG is a major trigger for many migraine sufferers.
Sunlight or light that flickers is another common trigger. So, always wear sunglasses outside. There are many others, you can find if you do a google search.
Avoiding triggers has helped tremendously.