I so glad you started this thread, OP! I thought I was the only one who got stressed about the small trips!
Like another PP described, I keep running lists and only go to the store once I'm out of multiple items. I'll often have DH stop on his way home from work for little things. Or we all go on his day off. Or I make him a list and he runs around for me. I have two kids, an 11 mo old and a 4 y old and its just annoying doing the carseats over and over. It wears me out. Plus we share a car, so I usually have to plan my day/errands out with DH the night before.
Wife to my sweet DH, SAHM to my princesses DD1 (4) and DD2 (1)