I'm going to second the advice to try putting your sleeping bag loosely in something bigger than the compression sack in came in, and start by placing that in the bottom of your pack. Same thing with your clothes and tent, put them each loosely in their own bag and put them on top of your sleeping bag. Garbage bags work good, just make sure air can escape.

At that point your pack is going to be looking pretty full. Start cramming everything else around, in between, and on top of them. Use all your other gear to compress your bag, tent, and clothes. This is the first trick I learned for taking advantage of that pack.

Place the things you be getting at the most near the top of the pack and in the external pockets. On that Osprey pack those external pockets are very stretchy and they will hold a lot of stuff. Filling them up is the other key to using that pack.

I'm using an Osprey Talon 44 and a Kelty 20º down bag. When I first tried packing it I had the Kelty bag and tent in compression sacks and didn't take full advantage of the external pockets, and I didn't get all my stuff in it either. I can get a 3 nighter into it now.

You tent is probably bigger than my homemade tent, but so is your pack, so I think with a little practice you can make it work, and when you get it nailed down you'll probably have some room to spare. I did.