This is perfectly normal behavouir for a baby that age - they have no idea how long it is betwwen feeds and quite frankly, they do not care. All thy care about is that they are hungry and want to eat now, or tired and want to sleep NOW.
I used to write everything down and you will be amazed at how much routine they actually have after monitoring for about 2 weeks.
But you need to start off with observing the sleeping patterns, once you get that sorted the rest kinda falls into place.
As mentioned earlier, a baby that age should not be awake for more than about 90 minutes, give or take 5 minutes or so.
So even if LO does not seem tired, start with your "winding down" process after 90 minutes awake, in the beginning this may entail you sitting rocking for about half an hour, but LO will soon get the idea.
And leave her to sleep, this is when they grow, if she is hungry, she will wake up. Okay there are various views on this, but I found (with both boys) that if I woke them for a feed, they would be seriously grumpy.
Brandon was a bit harder than Liam to get the whole sleep / food thing going, but he was my first child and I had no cooking clue what I was doing.
But with Liam, it was a breeze, once i had figured out his sleepy signals and worked with the Baby Sense "awake time" rules.
And yes, it does sound as if he is switching day and night - try to keep noise at normal levels during the day, don't close curtains, so he is aware that it is day time.
Then at night, try not to have TV blaring, close curtains, have a sleepy time routine (eg. bath, bottle, bed) to differentiate between day & night.
And as for the feeds, yes try a bigger teat - it may be taking too long for him to drink as the flow is not fast enough for him. That might also reduce his night time feeds, as he would be getting more during the day.
But really, as tedious as it may seem, write down when he does what, how much he drinks per feed etc, it really helps, cos you will be able to monitor exactly how much sleep & food he is getting in a 24 hour period.
That said, you need to remember that the only predictable thing about a baby is their unpredictability