Is it possible to get a dry socket at day 10-11 after wisdom tooth extraction?

I've got 3 wisdom teeth extracted 11 days ago. I had an appointment with my doctor at day 7 and she said it was healing properly, told me to gently brush the areas and I clean the bottom one with a water syringe. However, yesterday (day 10) I ate normal food while being careful and I used a straw. After, I brushed my teeth and there was blood. Today when I look at the extraction site, there is now a hole and I see something white (maybe a bone?). Could it be a dry socket? Doesn't hurt though.