I have always wanted three kinds of dogs (shih tzu, yorkie and a maltese later on a golden retriever.). Never wavered in my decision on either of the dogs, but as one fellow poster said if you doubt now then I wouldn't put myself into that position to try to raise one.
If you really wanted one nothing anyone said here about any problem would make you change your mind. I was on this site for months before I found my dog and read everything and nothing made me doubt getting my Hooks.
As far as housebreaking goes
my shih tzu was impossible still is impossible and will always be impossible and will purposely pee if he is upset with me
but he is my baby so I deal with it and I just try not to upset him and he is pretty good after a year of working with him. Hooks pees on the pad 90% and poops on it 45% so we are already working on better odds.