Another alternative you could try is to use the same color (white or something to match your top) in both the top threading and the bobbin. If you have any "mistakes" on the back that you don't want to show you can always use a Pigma Micron pen in a dark blue to color over the threads that you see as mistakes---I've done this before and it works like a charm. You do then need to iron over the part where you colored the thread in order to set the pigment.
Your top is beautiful. I'm sure your quilting will be as well.
Rob
<object type="cosymantecnisbfw" cotype="cs" id="SILOBFWOBJECTID" style="width: 0px; height: 0px; display: block;"></object>