My LO is 9 months and 1 week old. Around 5 months and 2 weeks, we switched him to level 3 nipples. So he’d been on them for more than 3 months. He’s been drinking water and eating solids pretty well. So I thought it might be time to upgrade to leve 4 nipples which are marked for 9 months+. Also, he’s been splitting a 7-8 oz bottle into 2 courses recently, meaning we offer a bottle, he’d do 3-4 oz and then finish it when we offer again in 30 min. So I thought level 3 might be too slow for him. After we switched to level 4, he’s been finishing 7 oz in one go without any problems. The thing is, he finishes it within about 4 min. And he’s been hiccuping a lot in the last few days. Is chugging a 7oz bottle in 4 min too fast? Should we have stayed with level 3?