Is this possible to do?

I breastfeed my daughter at night(no formula) if she wakes and at 5am when she normally gets up through the day she will feed from me and have a bottle of formula maybe 1-2oz if she has fed from me before hand if not she will take around a 4oz bottle.

She will be 4 weeks on Sunday is it possible to take the bottle away and switch to only breast feeding or have I left it too late?

She was born 9lb 10oz after the first 5 days dropped 5oz then dropped another 5oz at 10 days old to 9lb so she is a good size.