I'm going to take a conventionally backwards approach and suggest choosing a pack size first since you are just starting out. I'm only doing this because you are a beginner and probably haven't made your final choices in other gear. The choice of size would be based on expected weather and length of trip.

Recently, I got a couple smaller packs. One is 44 liter, the other is 33. The bigger is $149 new and the smaller is $129. You could easily spend over $300 for a larger bag. By saving money on the bag, now you could afford to buy a down sleeping bag that would stuff compactly into the bag. Down would likely be the only thing that would fit, so you have been driven to a quality purchase.

You would also be driven to synthetic clothes which pack smaller and maybe a different choice in rain gear or layers to wear to stay warm. You will probably need a down fleece which will pack real small and is light. You will also have to learn to stay warm using layers instead of having a big parka.

On the 33 liter bag, space is limited. A small stove like a homemade alcohol stove would be a great option. For cookware, a little 2 cup pot would work great instead of that one liter Alpine set you may already have. You would have to learn to bring compact food with you instead of Mountain House or some similar brand with heavy bags.

The tent is going to be a bigger problem for you than the pack. With your size, you are probably going to need to use a tarp. Maybe there is a single person tent someone knows about. But whatever it is, with a small pack, it's going to have to be small and by default, light weight. The sleeping bag and down fleece will likely be the only expensive items.

If you can fit everything into a 33 or 44 liter pack, the weight will be low enough so you won't even notice it. Even if the fit isn't so good.

Think about where you will end up with one approach over the other. If you go in with all the wrong gear and ask for a pack, you will get one that fits all the wrong gear. Later, you will replace the gear and the pack. If you go in with the right pack, you will be forced into the right gear.

There are a lot of caveats that go with this approach. And most people stink at sales and won't able to help you.

The stereotype is that going lightweight means lots of expense, titanium, drilling holes in toothbrushes, and giving up safety. It can be all of these or none of these with choices in gear.

Think of us as as a salesperson with a multiple personality disorder. You will get a lot of opinions, and they will all likely be good. But collectively, we have a lot of time to help out if you can interact with us.