Baby Mary Janes

I found this pattern for baby Mary Janes. They are very quick, it took me about 20 mintues for each one. The pattern calls for an I needle but I used a J so they would be bigger. In the pictures I used the lion brand Microspun but I think it might come out better with a heavier yarn like the Caron. I want to make them bigger but I am not sure how to adjust the pattern. Here is the link to the pattern:http://www.geocities.com/gossgirl2/fakemjs.htm