Not ovulating

I haven't had a period since October, and when I saw my doctor last week she said I need to lose some weight to get my period back on track. If it doesn't start back up, she told me when to come back and we'll look into other possible issues. My husband and I are starting healthy eating habits and exercising, so I am working on my weight.
My question is, has anyone else had an irregular period (for any reason) and gotten pregnant and not realized it?