Increased metformin

Jaimee
So on Monday the 22nd I started taking 500mg of metformin and this Monday (the 29th) I increased it to 1000mg per doctors orders. 
Is it weird that I still am not experiencing any side effects from it? Occasionally I'll get a slight headache it I'll get nauseous if I don't snack throughout the day but that's about it. None of the terrible potty breaks, nothing. Lol 
Doctor wants me to increase it to 1500 mg next Monday and give that a try for a couple weeks. 
Anyone else not experience the side effects of metformin?