dummy at 2

So when my son turned a year old or might of been a bit before, we took his dummy away and only used it if he really needed it like my eldest child school plays lol but he still has it of a night time. Anyways he still doesn't talk..well he says mumma on the very odd occasion and loves to say yeah but that's it. I told myself I wouldn't allow my son to have a dummy in all the time like my other boy did as he had speech development issues but he did still talk a lot more than this one. I have noticed something though. When we go upstairs to bed and he grabs his dummy from the cot he is more likely to say mumma and babble. Just thought it was very strange surely it should be the other way around. I am constantly talking and doing puzzles and involving him in conversations. My other two love to read him books as well.. but just nothing seems to be progressing. I told myself I shouldn't worry as he will get there but he was 2 last month and my daughter at that age was singing the alphabet and my other son was saying a lot more words too. Just feels very different this time round. Not sure what to do :/