I hate following patterns. I'm one of those knitters who likes to knit by the inch. My typical mitten pattern, for instance, is: Knit rib cuff for 3 inches, 2 1/2 to thumb, 4 inches straight knitting until you get to the decreases. I think you get my drift.
I don't know if I'm blonde, or maybe it's been a long day at work? My poor little brain isn't fathoming this. How the heck do you get 18 stitches for 4 inches? That's like 4 1/4 stitches per inch. A quarter stitch? Maybe I need to take Suzee's advice and have a little glass of wine.
I've been winging this top down baby sweater pattern. Knitting Fool has a pattern generator, but I thought the stitch numbers were way off. What helped me a lot was this chart. I would get your gauge with the type of yarn you want to use. Get a flexible tape measure and measure your bust. Or get a chest measurement off a sweater or sweatshirt that fits you well. These percentages on this illustration might help you to get it right.