Decreased Appetite

Baby will be 7 months on 10th. Has anyone seen a drop in appetite with their babies? Mine went from eating anywhere between 6 1/2 to 8 ounces plus his baby food 2 to 3 times a day but has recently lost interest in his bottle and will only drink between 3-5 ounces but will eat all his baby food with no problem but I know formula should still make up most of his diet. He shows no signs of being sick and recently started eating at least 7 ounces per feeding plus his baby food but he has gotten fussy when I hold his bottle for him and he tries to hold it but has trouble getting the milk to flow back to the nipple, should I switch to a sippy cup to make it easier? and could his eating issues be due to teething?