Um....I don't geddit.
On the 'feed her at 2 am' side of the argument, we have:
You are happy.
Your baby is happy.
She is thriving.
She is waking up once, and giving you the chance to have a 'grown up' evening of reasonable length....and this pattern is more reasonable than many babies of this age (most babies, breast or bottle fed, are still waking up in the night and needing attention of some sort, at this stage).
She is getting the best food possible.
There is no (repeat no) guarentee that a bottle of formula will make one jot of difference.
You cannot 'make' a 13-week-old sleep through - I mean, you could ignore her screams, and she would get the message....but maybe you prefer not to do that.
She may well drop the 2 am feed spontaneously.
On the 'she should be sleeping through' side of the argument we have:
Some of the people you know or have met in passing would think it was a good idea.
I don't think the scales equalise out very well, do you???
Honestly, what business is it of theirs whether your baby wakes up once, twice or 10 times???
Tell them to take a hike.