What should I do?

lets assume yes. heavy weight circuit training when you are in the gym will help build muscle and shed bf. if you can squeeze 4/week great, 2 upper body days, 2 lower body days. change your treadmill time to 20 min of hiit. 2 min of walking at a brisk pace and 1 min of sprinting, all out. if you miss a gym day add bodyweight exercises to your home routine before doing the hiit treadmill work.

bf will respond to the heavy weight work and the hiit training, but consistency and paying very close attention to your calories is most important. eat at a small deficit so you lose bf and maintain muscle, keep protein macro high, 1g/lb of bodyweight.

if you need more detail in the workout, holler...

good luck, i'm sure others will have thoughts as well.

Yes, it's more like 5 days and if I'm lucky then 7 days of some sort of physical activity going on. When you say "upper body day" or "leg day" I worry about the weeks where I am only able to lift 2 days a week. This "My Fitness Pal" says I should be taking in 1350 calories a day (or something like that) and apparently I will lose 5lbs by April.

Will supplements speed up the loss of body fat?

I'd say stay away from "weight loss" supplments. Do it the old fashioned way, it'll feel better, cost less, and you wont have to worry about all those awesome side affects listed on the side of the pill bottle - Is it Alli that causes anal leakage?

Do any of you know of an effective upper/lower body routine? I want to eventually come up with my own workouts, but I don't know what things to combine or avoid...if that makes sense. Any samples I can look at/try out?

Note - you can pick and choose, add or subtract etc, but I would try and do a circuit of 3-4 rotations that included 2 exercises per bodypart, say starting out 3 sets 10 reps each.

Upper - Chest - any press (flat, incline, decline, machines ect) any fly (flat, incline, decline, machines etc), push ups (wide hands, narrow hands, normal hands, incline, decline, lots of options), dips
Back - pull ups (assisted if necessary, this is a great exercise) rows (any row machine, dumbells, one arm, both arms, long pulley, etc.) pull downs (machine, wide hands, narrow hands)
Shoulders - presses (machine, dumbells, etc) lateral raises (machine, dumbbells), dips
Arms - biceps - curls (machine, dumbbells, etc) triceps - presses and extensions (machines, dumbbells etc.), dips

Lower - squats, leg presses, leg extensions, leg curls, walking lunges...

Bodybuilding.com has pics and videos for most of these listed if you are unfamiliar. If you only get 2 days, then you have hit whole body by doing 1 upper and 1 lower. As the weights become easier, increase weight, or sets ect.

Success will be determined by your consistency, timing will depend on whether you are able to have more 4 days/week or 2 days/week. Diet is key and all this goes out the window if that is not solid... good luck..