Potty Training STINKS!!

Why is it so dang hard to potty train? Malia has been trained since the first week of January...but still has accidents all the time! I know she knows how to go to the bathroom and everything and we don't have any issues with being scared, etc. So what is the deal?? It is so frustrating and embarrassing when she has accidents, especially at other people's houses. We've tried the sticker thing, rewards, praise and not giving her the attention when she has accidents, etc. She knows that she is supposed to go on the toilet. She will do really good for a few days, then two or three days in a row with an accident. And she just looks at me and smiles and says 'I pooped' then waddles into the bathroom and takes off her clothes. Most of the time she is IN the bathroom standing in front of the toilet when she has the accident. Ahhh! I just don't get it. I guess this is why they say it can take months to totally potty train. I thought we were so lucky because she did it so quickly and easily in the beginning...and didn't start having accidents till almost a month later. And every few days since!