Start Breastfeeding when baby is older?

Debora
Do any of you moms have had a baby that latched when older ? 
I had to feed my baby formula at the hospital because my milk didn't come in and he had jaundice and wast having bowel movements. He is 6 weeks today and I have been pumping and giving him the bottle but he refuses the breast everytime I try.
Should I stop trying since its frustrating for both of us or do you guys know of any baby that started breastfeeding later on?
Thank you !