Hi there - congratulation on successful breastfeeding to 6 months. Are there other factors surrounding your interest in weaning your baby or is it just lack of sleep? You have done so well so far, if you can continue another six months of breastfeeding, you will have given your child an excellent gift (not to mention saved yourself hundreds of dollars on unnecessary formula - which your child could reject or have an adverse reaction to).
There is no reason to wean at this point. Your child still needs to eat during the night - even up to 9 months they need to potentially have one feed. You're right, breastfeeding her is SO much easier, especially in the middle of the night when you don't have to fuss about making and heating bottles (never mind it sounds like your daughter has no interest in taking a bottle for you).
I found it so much easier to breastfeed my son when he woke at night as not only did it satisfy his hunger, but the suckling he gets at the breast has a calming effect and would put him back to sleep within about 10 minutes at that stage.
What I would do is perhaps research some sleep techniques that you can use to help your daughter self-soothe back to sleep and only call on you if she is indeed hungry. There are a couple of books I would recommend - the No Cry Sleep Solution or Happy Sleep Habits Heatly Child (by Weissbluth). 6 months is a good time to start thinking about sleep training, but as I said, your child may still need a middle of the night feed right up to 9 months old.
She will go for longer stretches naturally in time and in the grand scheme of things, this is a blip in time (though, I work full time and know full well how tired you are!). Things will get easier, but have a look at those two books and don't wean yet - there's no need to do so!
Good job mama and best of luck!
PS - NEVER add cereal to a bottle - it is a choking hazard.