my little girl is now 17 weeks, and she started being fussy during feeds about the same time, although not accompanied by sleeping through the night

! I thought it might help if I shared some of my thoughts about this issue .....
I think around this age she became far more opinionated, and decided she did not like my slow-feed side when she was hungry (I think many women have a side which is faster and one that is slower). We now do that side second, except her dreamfeed and 4am feed, when she does not seem to mind.
She also became more aware of what was going on around her and very distractable, so we now feed somewhere quiet and peaceful - even her Dad's voice is enough to distract her and she will pull off the nipple (sometimes flinging her head in the direction of the sound while still latched on - ouch!).
She also started feeding so much more efficiently at the same time and that really confused me - I kept trying to put her back on, worried she was not reaching the "hind milk" and that just frustrated her. 30 minute feed sessions seemed to go to 10 minutes overnight. But I have had her weight checked and also tried expressing after these short feeds and she really does seem to be finishing in a very short time.
I also moved her to 3.5 or even 4 hours between feeds, which improved things: I don't think she was always hungry when I was feeding her and was then very frustrated that she was being expected to feed when she did not want too. However, I also found feeding her when she was really hungry was not ideal becuase then she was really tense. I have started being very vigilant for the little poking out of her tongue which signals she is hungry and feeding her then. despite moving to 3.5 or 4 hours between feeds, I kept her sleep times almost the same at first, because she still needs to sleep after 90 mins or so of being awake, although this is continuing to gradually lengthen and we are now at 4 months moving onto 4 hour easy.
She does still bob on and off, but I have learnt to go with the flow and not fight it too much. I try to put her back on a few times and then stop if she seems frustrated. Sometimes I try her again after half an hour, and occasionally she will take a bit more then. I find she is most relaxed if she feeds immediately after a nap when still a bit sleepy, or just before a nap for the same reason. Its most difficult in a noisy cafe or when there is lots of noise around or in a strange place. Dream feed and night feed are fine.
hope this helps
Sarah