I given mix milk also but after 3 month I used all bottled feed even for bm for my gal to get used to..she will always fall asleep if latch on and wouldn't be drinking enough for her and will wake up freq so before sleep time I will give her formula so she will have enough sleep for both me n her...and day time bottle bm for her to get used to so she can get ready after I start work.
No need cos it's totally normal! My baby is a mix feed baby too till today, 7 mths old. Sometimes he'll reject fm and prefers to latch and vice versa even till today. Totally normal. Many mums are experiencing the same. Can be very frustrating & worrying but it's nipple confusion for babies your age.