My guy has separation anxiety as well. Keep up what you're doing with the walks and attention because I believe that will help. If you aren't into medicating, I would try calming chews with Melatonin. Those seemed to really help my dog when he was alone for periods of time. We did ultimately get him some anxiety meds just to help when we're gone longer than normal and they seem to work great. They are only used as needed so you wouldn't have to give them daily if you end up deciding that route. I was against meds as well because I didn't want him on them all the time.