Child never says "Dada"

Hi, I'm a mum to a 17month old little girl (17m as of 28/11).She's generally happy, and despite having a 5 day stay in hospital for a chest infection last week, and not walking yet due to hip dysplasia (clicky hip) she's generally well behaved, and described as a delight by the staff at her nursery (daycare).However I have noticed that she never says "dada" to describe my husband (her dad). She uses "mama" for mummy (me) and "gaga" for grandma (Mother-in-law), says "baba" to describe her blanket (you can tell her to find her blanket and she'll say "baba" and crawl off, if you ask what blankets called she'll smile and say "baba"). She also is starting to say normal words, her favourite being "hiya" which she says to everyone who so much as smiles at her. She also says "Byebye" and will use "my" when talking about something - so when I pick her up from nursery she might hug me and say "my mama".But she never ever says "dada". If you ask her where daddy is she looks at my husband, and she's happy to be with him - will watch TV on his lap or will play with him - he helps with bedtimes, bathtimes and general parenting.So why doesn't she say "dada"? Is it because my husband is just as involved as me so she sees him as a second mummy? Or does she just not like my husband and prefers her mummy and grandma?Or am I overthinking it? via /r/Parenting http://ift.tt/2ghPZM4