That's weird that the velcro has fallen off.
I use the heavy-duty velcro for my picture hanging (it's about 2" wide, black and wickedly grippy to the point that removing the pictures requires running a knife through the velcro to make it release or the back of the picture frame pops off) Maybe try the velcro again but prepare the surface more? Do you leave your pictures up while travelling? Maybe you need to take them down except for the picture on the bathroom wall. And only use picture frames whose backs are flush or nearly flush with the wall so the velcro can really attach.
Vicky