I think I understand this. On the inside of the waistband, anywhere, cut a vertical slit in the inside layer of the waistband and pull-out the elastic (if you can) and put a seam in it making the waistband tighter. Remove excess and tuck elastic back in band and close slit. You may not need to remove any of the material. Then make the side seams bigger as you say. That might do it for ya! If the elastic is sewn INTO the band this won't work, sorry.

Salena, Thank you. I will need to take in excess fabric as well. Should I use the smaller size as an exact template (we're talking about 2 sizes down)? Also in looking at these shorts, the elastic that goes all the way around has 4 sets of stitching (horizontally) thru the elastic layer so I guess what I think you are saying, doesn't apply here. Thx Again, Nicole

Is the elastic covered by the waistband or sewn to the outside of it? If it's inside the waistband and you don't mind spending the time, you could take all the stitching out of the waistband(you may have to remove it from the shorts). Adjust the width of the waistband to match the new width of your shorts, sew it back on the shorts(if you removed it), fold it over and make a casing that you can pull your elastic through and adjust as needed.
If the elastic is sewn to the outside of the waistband, you might get away with taking it in along with the side seams of the shorts. Just reinforce your stitching(stitch over it a couple of times) so it won't come apart and trim fairly close so it won't feel bulky. Good luck. I hope I'm not confusing you.

My suggestion now is to try and find the correct size short. I think you will NOT be happy with such alterations especially since the waste elastic is not 'free'.
Salena