Is it bad of me to keep my contacts in this long?

I've been wearing contacts for a year now. I wear "Air Optix Day & Day Aqua" so they are safe to wear at night. They are a monthly prescription though and I've been wearing them for 2 1/2 months. I got tired of taking them in and out to clean them and then when I would clean them the solution would sting my eyes and it just always seemed like a pain so I decided to see if I could just keep them in for a little bit. My eyes feel perfectly fine, I never get anything in my contacts and my vision is still the same as it was when I first got contacts. So I'm wondering, am I harming my eyes by wearing my contacts so long? Even though my eyes don't ever feel dry or irritated?