6 month old not sleeping

My son is 6 months. Exclusively breastfeeding. He eats every 2 hours during the day, usually has 2 naps both being an hour long. At night, he still wakes up 3, sometimes more, sometimes 2 times, to eat. Sometimes he will stay up for 2 hours in the middle of the night wanting to play. We have a bedtime routine every night & i do rock him to sleep, which is probably the issue.. With my first, he was sleeping through the night by 3 months & by 6 months, I could lay him in his crib and walk away and he would go to sleep on his own. Can I sleep train him now that he is 6 months? Cry it out method? Other methods? I’m growing very tired & my patience is running very thin.