6 month old sleep problems

Mamas, I need some advice. My boy is 6 and a half months old now and simply won't go to bed before 11-12 pm doesn't matter what we do. He used to sleep 10-12 hours at night and about a month ago he started waking up after I put him to bed. First I could put him back straight to bed after a minute of rocking, after a few days it took 10-15 minutes, after he didn't go back until 11-12 after eating again (more like comfort eating) and now he doesn't even go to bed at all. We have a bedtime routine since the beginning and he always falls asleep while breastfeeding after bath. Lately he is sleep eating for 35-45 minutes and he is bright awake after. He is napping good during the day and once he falls asleep he is down for an average of 7-9 hours.