It’s our job to worry and advocate for our children at every stage of their development. That said though, I don’t think you are being fobbed off. I have been in a very similar situation with my AS. He moved in at a similar age, was at a similar stage at 15 months and history of ld in the bf. I think it’s true that the move sets them back a bit developmentally, or at least pauses development for a short while while they adjust.
For me I think I clung onto the ld more than I needed to, certainly more than was helpful, but I simply wanted to know and delayed speech was a red flag in my mind. I raised it with three different SaLT therapists and a paediatrician over the course of over a year and they all said it was too early to say whether his speech delay was a result of ld. They also consistently said that he was too young for SaLT work, even at two and a half when he had some words and phrases, but limited sounds and just didn’t seem motivated. He was about a year behind his peers, but apparently not far enough to be a real concern. The bar is quite low for SaLT intervention. Just before three and a half he was assessed again and they agreed he was now at an age/stage that SaLT would be beneficial, but a month or so later when the first session came around he had progressed so far that he was discharged. Now, a few months later, his vocabulary is through the roof. Yes, he is a little behind his peers with his range and he is still working on a few of the harder sounds, but he is chatty, confident, sociable, tells me about his day, tries really hard to communicate, even ‘reads’ aloud and is generally an absolute joy to be around. To the question of whether he has ld, it’s possible, but I’ve accepted that it’s too soon to say and it’s no longer weighing on my mind.
I think if you saw a therapist at 15 months all they would really focus on is how you are interacting with her. That you are reading with her, singing with her and always giving a commentary on what you are doing in really simple language: I am cuddling the teddy, here is your bottle, etc. This is what you need to be working on now to give the best chance. That said, I did all of this and my DS was still delayed so it is definitely not a quick fix. It definitely all helps long term though. I don’t like to think of where he would be if he hadn’t had it.
You could also try some Makaton. You don’t have anything to lose, as it won’t delay speech if you are using it in addition rather than instead of speech and can actually help it along. It may also be the tool she needs to understand and be understood if she does have a few difficulties later on. We came to it a bit late so my lo did pick up a couple of signs, but ultimately decided he would rather just say the words, which was great.
I don’t have any experience with glue ear. I have had moderate hearing loss in one ear myself though. If the hearing loss is mild then she can still hear, and as you said she has good understanding. So it’s more important that you are talking to her clearly and directly, face to face so she can see your mouth. Keep background noise to a minimum as this will make it more challenging. You’ve mentioned an audiologist, but has she seen am ENT specialist? I could be wrong but I don’t think they would operate on such a small child, but the specialist will have far more knowledge and understanding of likely causes and treatment than audiologists and may be able to put your mind at ease. This is what I would be pushing for if you don’t have it already. Your GP can refer you. And obviously keep the appointment with the audiologist in three months.
Above all, do try not to worry. Your baby sounds like an absolute joy. They do develop at different rates and it is really early days. Most likely she will be absolutely fine.