Since your bubbles are transparent, there should be a light reflection on the inside back of them, not just on the surface.

Here are a few bubble photos - Notice the light reflection on BOTH sides of the bubble:
http://www.everystockphoto.com/photo.php?imageId=2560150
http://morguefile.com/archive/display/126802
http://www.everystockphoto.com/photo.php?imageId=1641885
The interior bubble surface is actually reflective, like a spherical mirror. For 2d rendering, it is usually sufficient to just have a light edge along the opposite side of your light source, or occasionally a smaller "reflection" of it, when it is a square-ish shape like a "window" shining on it, or in this case, a round-ish "sun," 180 degrees opposite.

The exception to this is when a bubble is in liquid, like water, or champagne. Then, the light diffraction of the liquid creates a dark edge on the opposite side of the light source:
http://www.everystockphoto.com/photo.php?imageId=661570

Hope this helps!

second thought, i don't think my bubbles need any work, they're my own fictional bubble that I created, they don't have to be perfect..I do take your advice thoughtful though, Thank you.

No problem at all! Best of luck to you.

Beautiful bluish work...GL author

This could make a very nice wallpaper

thank you Cornelia!