How many bottles does your baby have a day?

Hi, my baby is 11 weeks old and has fallen into a good routine but im finding the feeding times difficult. She currently has 6 bottles a day starting from 7am and is normally fed every 3 hours during the day. So currenty she is fed at 7am, 10 am, 1pm, 4pm, 7pm then dream feed at 11pm. She leads the times and is normally ready for a bottle at these times but in last week we have noticed that she wants to go to bed at 6pm-6:30pm and gets really grumpy until she does. If we leave it too late she cries and refuses her bottle as she is so tired. The problem is the time from 4pm bottle and 6pm bottle is only 2 hours so she only takes 3oz when normally has 5oz. I have tried making 6oz bottles and thought we could make it last longer like every four hours and would work out but she normally stops at 5oz. She's really happy and I think she just really likes to follow a rountine so should i just stop worrying?? Any advice would be great x x x