While it could be digestion issues, the things you mention here could also just be normal 3/4 month old baby issues, whereby they all are hard work to get sleeping independently. For example:
when we feed her she seems to be moving her head from side to side with her bottle which i think may be contributing to her wind
Side to side head shaking is a classic and very common over-tired sign. It is a way baby is trying to self sooth - a sign of frustration. Imagine baby saying "for God's sake I'm exhausted and need to sleep right now. HELP ME SLEEP".
To solve it and reduce the head shaking, get baby to go to sleep earlier. Tgis is a very late over tired sign, baby probably needed to be asleep an hour earlier.
when she cries we pick her up and she will pass either wind or burp.
Crying causes baby to swallow air, so crying itself causes wind. It might be that if baby was sleeping better then there would be less crying, so less upset.
Also, that baby does trump or burp periodically is not in itself a problem - they do this naturally.
has issues with sleeping in the day where she has to sleep on us
I would say a good three quaters of all under 6 month old babies have trouble sleeping in the day and that parents have to work very, very hard to get baby sleeping independently (ie not in your arms). So again, if you're using this as an indication of There being something medically wrong, it may not be the case at all.
We were thinking of changing her formula but what are people's thoughts on doing this now at 15 weeks
Assuming you've not had anything medically diagnosed (for example allergies) then I'd be weary of doing this from what you have said here.
Your baby is feeding well and sleeping very well over night. Rocking the boat may change that.
We have tried everything in the day and nothing seems to work
Firstly - be aware of awake windows. Baby doesn't want to be awake for more than 2h in one go at this age. And work out the ideal time for the next nap as: awake window = double previous nap length, plus or minus 15 minutes.
Getting an over tired baby is significantly more difficult than getting baby yo sleep before they get to bring over tired. Any outward signs of tiredness (face rubbing, head thrashing, yawning, red eyes) usually mean baby is now too tired and could have done with being asleep at least half an hour ago.
With that sorted, accept that babies need a lot of help to get to sleep. So you will have to work at this, be consistent and keep trying. Two well established things that help baby sleep:
Sucking. Nature's way of calming and soothing baby. If not feeding to sleep I would keep trying with the dummy. Because without sucking yo sleep you more often than not get crying to sleep if you are wanting independant sleep.
Movement. The independent way to do this is to put baby to sleep in something that moves, rather than in your arms. My favoured option would be the bouncy chair. Or pram.
Be relentless and non-stop about it, to get baby to sleep initially. Even tempo and continual. Then slow down and stop movement when deeply asleep.
Again remember, if you're not using movement alongside a dummy then you're most likely going to have to deal with baby crying. The crying is just telling you baby they want to be asleep.