Hi there and welcome to Moomie
I agree, first exclude any medical causes for night wakings. If she has been cleared by the GP/ paed the guessing game begins

Babies looove waking up for loads of reasons...and they're usually one step ahead of us!
Firstly, she may just want to be close to you, her favourite comfort item - especially seeing that you are still breastfeeding her (which is awesome!). Have you considered co-sleeping and feeding her while lying down? Might get you both a better night's rest as neither of you has to wake up fully.
Teething can always be the culprit. My little girl is an exceptionally bad teether and nothing has helped except homeopathic Chamomile powders! But you can try rub-on stuff such as Prodol and if all fails you can give some Nurofen to help reduce the inflammation.
Then they also like to wake up when they have reached new milestones such as sitting or crawling etc. but also cognitive milestones. Many babies continue to practice in their sleep. These phases usually pass after a week or two.
It's quite common for babies to sleep through at 2-3 months and then all hell breaks loose as everything in their lives becomes so exciting

Their are certain sleep regression phases (4 months which can extend to 6 months and 9 months are the most common ones). If you are in favour of it, you may want to try (no-cry) sleep training, there are lots of different methods - google is your friend
Good luck!