Good morning! Ang 15 months is a bit late pa para sa bottle weaning talaga, pero don't worry, a few of us tried different approaches and what worked best is going slow lang, like offering the bottle during meals habang may solid food na siya para may distraction. For formula, honestly most of my mum friends either use S-26 or Lactum depende sa budget, pero ang importante talaga is na consistent ka sa brand para hindi mag-upset ang tummy niya, at yung bottles na may soft nipples (like the wide-neck ones) ay mas accepted ng babies kaysa sa traditional bottles, try Philips Avent or Tommee Tippee kung may budget, pero kung tight ang bulsa natin, ang regular bottles ay okay din basta gawin mong fun at hindi forced!