Hi KenDee,
as a fellow asthmatic who received similar advice as a child, I can appreciate how you feel about what you've achieved so far, and about not wanting to lose it.
You say you're trying to build upper body strength for next year - is this for something specific?
Also, what weights programme are you planning to follow in the gym? It looks like you're planning 5 sessions a week, if you try to do weights every session you'll probably end up overtraining and injured (don't know how much weights work you've done though so if I'm making an assumption and actually you've been body building for a decade then I apologise).
A suggestion would be:
3 weights sessions through the week, Monday, Wednesday, Friday, concentrating on upper body. Split between 1 session concentrating on shoulders/arms, 1 session on chest/back, and one session lower weights/higher reps covering the entire body. On Tuesdays and Thursdays, use the 45 minutes for CV work, either on the rower, the treadmill, or go to the gym, get changed, run out the front door and do 30 minutes running in the real world (much nicer than a treadmill) and run back in for a shower - in other words, keep the running in but use the gym facilities to stop you smelling antisocial at work in the afternoons.
This type of split has worked very well for me, as it gives the various muscle groups enough chance to recover between workouts.
Another technique is to find out how early the gym opens in the morning, and try to fit in a run before work, again using the gym just for shower facilities.
You can probably tell from this that I struggle to find time to fit in training as well....
Let us know how you get on - I know you say you've no real drive to race but you may find that all changes in time, particularly if you keep reading the forum....