Hi, Pigwig, I'm a veteran migraine sufferer. Been getting them since I was 12 and still going strong in my 40's. I don't get aura very often now -the last one was driving round the M25 - eek! There can be lots and lots of triggers, food, bright lights, perfumes, hormones, almost anything, really. My particular trigger is missing a meal.
To try and identify your trigger/s it's worth keeping a diary for a month or two. Note down in brief everything you do. Time you get up, what and when you eat, any problems and of course your migraines, how severe and how long they last etc. Looking back over the weeks you may be able to see a pattern emerging and help identify the cause.
You don't say whether your aura is followed by a headache/vomiting. If it is and you need painkillers, take them as soon as you have the first twinge or flashing light. Don't wait-and-see, because you're far more likely to nip it in the bud if you medicate at the first symptom.
It's definitely worth seeing your doctor as they can give you good painkillers and preventers these days and also the Migraine Society is useful. Alternative therapies are worth considering. I've had a course of acupuncture which was quite good and have begun reflexology. Feverfew tablets are of use to some sufferers, as well. HTH