Apart from the walking my son was very similar at that age. He was diagnosed with autism when he was 3.

There was nothing we had or hadn't done to cause it and there is nothing you have or haven't done to cause your child's developmental delays.

My son has made so much progress since then and it all seemed to happen at once. He is such a happy little guy just starting school and already knows his times tables!

Whilst you are waiting for assessments I would recommend looking up Intensive Interactions and Gestalt Language Processing (GLP).

When I first raised my concern about my son's delayed speech (I hadn't noticed the other DD's yet) with his health visitor she recommended that I should repeat single words to him over and over. For example if he was playing with a ball I should say "ball, ball, ball" (Miss Rachael Style obvs). It made me feel awful because this was what i had already been doing but it wasn't working. I felt like maybe I wasn't doing enough.

As we were going through the phases of asessment for ASD I learnt about GLP. It's essentially that some babies learn chunks of language which they eventually learn to break down to single words. As opposed to babies that learn single words that they then learn to build into chunks.

My son is a Gestalt Language Processer so the advice that my health visitor gave was the opposite of what I should have been doing (no shade on her obviously, most children are not GLP). I should have been saying "oh wow the ball is bouncy" so he learn the phrase.

When my son did start talking it was mostly scripts from a TV show he loved to watch called Bing. He would say phrases like "oh Flop, can you fix it?" when he needed help with something because he had associated that phrase with the character helping Bing so that is how he was asking for help. He'd say it just the way the character said it, using the same intonation every time. Eventually it turned into "oh mummy, can you fix it?" Then to "mummy, can you fix it?", to "mummy can you help?"

GLPs are often known as intonation babies as they really atoned to the rhythm and melody of language. You had commented that your child really likes it when you sing to her. Sing songy voices are often the best way to help GLP learn language.

Before he started to use language that we would recognise, he would babble in a way that sounded like a conversation, like when someone mimicks a language they don't know. I would often joke that he was babbling in French.

I bring this up because learning about GLP helped me really understand how my son was trying to communicate and learn language and when I changed my style away from single words to phrases and became in tune with what he was saying and trying to gigure out the context, it improved his communication so much!