I think you and I might have the same problem I have a bowel movement about one a week or every 2 weeks.
I would talk to your doctor, or a few, to determine what the problem is. Do you stay hydrated and have you tried taking laxatives? Hopefully one of the doctors here can offer more insight but I would check with your PCP and get a stool sample taken.
Take a good prebiotic and probiotic daily.
Don't buy commercial ones, visit an organic food store and buy bottles from from a good brand.
Prebiotics (like MOLKOSAN) make sure the environment is good
for probiotic to multiply and sustain themselves inside your digestive system.