Backpack size - osprey sirius 24 too small?

Hey Team! I bought a osprey series 24 from REI and it fits really well and I love the color. I’m pretty petite, like very visibly narrow and weigh about 110 pounds/5’4. I’m very nervous about weight and have been training with my backpack walking around the hills in San Francisco. I also have the 34 and just slightly concerned about how big it is and if it will cause me pain curious if you have any thoughts about how necessary it is to have a bigger backpack if I plan to pack lean though with a small or ultra light sleeping bag.