Sugarplum,
I don't think you are being a hypochondriac at all. I think your questions are really appropriate. Unfortunately, I don't have any good insight to provide. I'm on 30mg of Adderall XR. I don't experience evening crashes, I only feel like I crash on the days that I don't take it. I'm usually fine when I don't take it until about 4 in the afternoon, then I seem to crash hard. I don't really experience this type of crash when I take it regularly. Have you experimented with taking it a little later in the morning? This way your crash occurs later when you can just relax on the couch after a hard day of work.