At that age, 3 meals per day are appropriate and I wouldn't recommend feeding less often. Your dog's stomach doesn't have the capacity yet. Stool volume depends (among other things) on the digestibility and fiber content of the food you are feeding.
If there are accidents, you aren't planning your dog's potty schedule correctly. Keep a journal and write down the exact time you feed, water and give treats. Also write down every time you take your dog outside to potty, whether she peed or pooped, and the time of any accidents that occur.
Within a few days you should be able to very accurately predict when your dog has to go outside, so you can prevent accidents.
Also, never let your dog have run of the house unsupervised. If you can't keep an eye on her, crate her or put her in an exercise pen.
The more accidents your dog has, the longer it will take you to housetrain her. Preventing accidents from happening is key.