>>2722522That's why we've been telling you all the time to buy your backpack last. If you want to use synthetic sleeping bags (like the one you've presented) and/or camp during winter and carry enough food for a week, then a big ass backpack is essential. I have a 80l army bag just for that.
First, see if you can compress it more. Do you have some backup straps or rope to squeeze your bag? Big part of it's volume is air, so that should help.
If that didn't help enough, then you could use the straps at the bottom of your pack to tie your sleeping bag to it in a pinch and carry it outside of your backpack. It's not gonna be a comfortable solution, but it could work. Just put a plastic garbage bag inside your stuff sack to protect your sleeping bag from getting wet.
Finally, if you're handy with a sewing machine and have one, then you could try converting it into a mummy style sleeping bag or even a quilt. DIY is the most based way to go. If you have a sewing machine available, but don't know how to sew, I highly recommend you to learn it - it's so braindead easy, that even women can do it.
