It's been more than 2 years since my last period!

My son is turning 2 years old at the end of this month. He nurses 3-4 times a day for maybe 15 minutes each. Occasionally he will nurse more frequently, like every hour for 10 minutes about once a month before a growth spurt/when he doesn't feel well.  
I have absolutely no period. I have had light spotting. I also drink/consume soy products. I'm starting to feel like a freak, not menstruating like other women do. What are your thoughts?