Does not make any sense at all! Whoever said that to you, pls, he/she is only frightening you with myths that are not even true! Your baby knows you're his/her mum even while still in the womb. Formula or breastfeed, your baby will still clings onto you like superglue! My 4 kids are formula fed and we are all very close since they were a baby. My now 8 mth old baby is a mix feed baby (fm + bm) and I'm his bestfriend. He only looks for me and only me when there are others at home. Which part is the 'will not be close'?
But not too late if you want to switch to nursing exclusively. Breastmilk is still the best but needs alot and alot of patience and endure alot of pain if the latching is not correct, the sore/cracked nipple. Don't force yourself if you cannot breastfeed