My son was exactly the same, with the delayed speech and tantrums due to frustration. He started nursery at around 14 months and that early exposure didn't stop his speech delay from occurring. At age 2, he was only just getting green on the 9-12 months expectations on the WellComm assessment. Nursery did a speech therapy referral around his second birthday. He's 4 next month and we've just had an email to say he is nearing the top of the list for 1-1 therapy.
His speech started to improve around his third birthday. We knew what he was saying but lots of others didn't. Now he's almost 4, and whilst he is definitely still behind his peers, his language is so much more improved. His main problem is "backing". He pronounces letters that should be produced at the front of the mouth (such as D, T, R) at the back, so says gaggy for daddy, replaced his Rs with Ys (he pronounces red as yem - "my yem car"). This is what he's awaiting on the 1-1 therapy for. He was seen by the SALT Team in November 2022 for the assessment after being referred in May 2021, and from that November appointment, he was placed on the waiting list for backing therapy.
If her nursery haven't already, ask them to do a WellComm assessment and make the referral. There's such a huge waiting list and it's really beneficial for them to be seen before they start school. At 2.5, school feels a long way off, but it comes around very quickly when on a waiting list.
My son is doing so much better than he was two years ago and I can have a full conversation with him now, but that's because I understand the replacements he makes, or the letters that he drops because he can't think of a replacement that sounds similar. To help him, I talk a lot. I narrate what he's doing (as advised by the SALT team when first placed on the waiting list). "Now he's got the blue block and he's putting it on the orange block / he's making a tower / we are walking to the bathroom" etc. We also do lots of story time and as well as reading the words, we describe the scene in the picture and as time has progressed, he's now taken over describing the picture.
It takes time, but they do get better (and then they don't shut up
)