craftgrrl | I sewed a new shirt!

Well, this is the first made-from-scratch shirt I've made since I was probably ten. I figured out a pattern myself form a picture of a shirt I liked on the internet. My question is: The neck kind of right against my throat and the "boatneck" is a little too wide, showing my bra straps. How can I fix both these problems but still be able to fit my head through it. I have dreadlocks, so my head is kind of large with all that hair. I was thinking that I could cut a little notch in the front and sew around that, but I don't think that would generally fit in with the style of the shirt.
If anyone is interested. My rough pattern is (adult small-ish) basically t-shaped. Pattern and pics under the cut.

Pattern: I made both the front and the back 38" across the top (this will be from sleeve to sleeve), then down 12" on both left and right (sleeve openings), then cut horizontal to top inward 10" (bottom of sleeves toward bodice), then down another 5" perpendicular to top. So, the bottom of each piece should be 18" across. Then, cut some spandex or stretch fabric of some kind for the bottom band. I made mine 13" tall and 30 inches around. Of course it is folded in half on the actual shirt. I started by sewing the hem of the sleeves and the necklines. I made the neckline 14" across, so I just marked my midline and hemmed 7 inches on either side of that. then, I just sewed the two sides together on the top and under the arms, and then put a gathering stitch on the bottom so that I could attach the stretch material without as much difficulty. Good luck!