8 month old not finishing bottles

My almost 8 month old(will be 8 months tomorrow) is a very hard baby to feed.  Here lately she will drink her bottle well then just abrubtly stop drinking and turn her head and you can't get her to finish it.  Sometimes I put her down wait 10-15 minutes and then she will either drink more or finish it.  She also will not eat puree food so we are going the baby led weaning way and letting her feed herself which you all may know she isn't eating much that way either.  She drinks breast milk and has been all her life.  I have been an exclusive pumper since she was 7 weeks old.  I just worry she's not getting enough food for the day. She was having 4 6oz bottles and 1 7oz bottle(bedtime) but has recently started sleeping all night so now she's getting just 4 bottles during the day.