Why 3 stall? Based on square footage of your house 2 stall is plenty. Looks like you have plenty of frontage to do L-shape as Brandi suggested but I don't think it will add to curb appeal, it would over power the house.

Any garage in the front of that house would be Jimmy Durante's nose. It would be an obvious curb-unappeal. If you cannot do a side load garage from the other side of the property, then your options to both have an addition be attractive and provide an over abundance if space are going to be limited. A 3 car garage would end up looking bigger than the house. It may be time to explore moving if the existing home does not provide you with enough space.

Also consider what the zoning rules are in your area - often there are limits on how far forward to the street you can build, as well as how close to the side property lines (can't tell from your pic how close the neighbors are). But I agree that a 3 car garage will look out of proportion. Frankly I think a 3 car garage looks out of proportion on most houses, though, regardless of size.