Hello, I am vegan and have a 5 month old baby boy. He too sometimes goes longer than a week before he has a bowel movement.

This site: https://kellymom.com/hot-topics/newborn-nursing/
States After 4 – 6 weeks, some babies stool less frequently, with stools as infrequent as one every 7-10 days. As long as baby is gaining well, this is normal. Wet diapers: Expect 5-6+ wet diapers every 24 hours.

It’s perfectly normal. If your worried you can give 1 once of apple juice to help with constipation.