My daughter...the master manipulator...HELP!!!

We we're not going to potty train until the new baby got here, but Makenna has taken it upon herself to get busy. We went ahead and bought her a potty chair (which she refuses to use...she likes the BIG potty). We bought her big girl panties (pull-ups). And started rewarding her with an M&M everytime she went potty.

Well... We are going on 5 days with a great record. Still no poopies in the potty, but no wet pants! Our problem now is the M&M's. She now runs to the potty every 10-15 minutes saying she has to potty, we sit her on the toilet and she goes maybe 2-3 drops procalims herself a 'good girl' and then holds out her hand for the M&M. Now she is only doing it for the candy. She isn't 'holding' her pee-pee so that she goes all at once, she is seriously going every 10 minutes just a few drops. If we dont give her the candy, a major tantrum errupts. I don't want her to quit pottying b/c she isn't getting her candy, but I also dont want her to think she can eat candy all day long for going pee-pee like 3 drops.

What do I do??????