My diaper bag is about 9 months old and the shoulder straps seem to be breaking down already. This seems odd to me since my bag has stroller straps and I carry the bag about 90% of the time using the stroller straps. I use the bag every day. I have a warranty, but kind of doubt they would replace the bag for this. So I'm wondering, how has your diaper bag held up, or how long do you think it should last?