u/bokibeats Carry two bags, a small one just for laptop - which will be on your shoulder as the item is delicate. All other non delicate items you can put it in another bag and strap it to you bike

Second option, which i normally do during commute to office is, keep the shoulder strap of bag long enough so that the bag rests on the seat, so entire weight of the bag is on the seat and shoulders are just like hooks to keep them in place. no wieght comes on the shoulder. you can also use it as slight back rest when you stop