I have a 5 year old with a speech delay. So I’m going to concentrate on the speech delay rather than the potty training as I think that’s been covered above.
I agree with everyone above - 1st stop is a hearing check.
You are already under a speech therapist - this is good, trust them. They know what they are doing. It will take time. Years in fact.
Learn some makaron
https://www.makaton.org
There's also loads of useful people on YouTube just search “How to sign X in makaton”.
If you pick out the most needed signs and use them all the time (and I mean ALL the time) your DC will pick up on this and start copying/using them to communicate.
Makaton does not delay speech further, but assists with essential communication. It can encourage communication as well as they feel like they are involved/achieving/first steps in communicating.
Model correct speech all the time, making sure to try and correctly pronounce everything including the word endings (which was difficult for me due to a habit of my accent).
Don’t second guess what your child is trying to say and don’t talk for them (unless absolutely necessary). Accept head nods and shakes and points and ask questions that only require those types of responses. Once this is fluent/confident build on this by adding in choices and making use of the makaron signs they know. Gradually you build up the complexity of the questions you ask.
Pictures are a wonderful thing. This was something we started at around age 4 (and was actually an something that came about after joining the Squirrel Scouts). Have pictures of what they have done in the day (general ones you can find on the internet are fine covering things like reading a book, playing a game, eating etc). Get your child to find the picture and put them in order for the day and then get them to talk through it picture by picture. You have to ask a lot of questions and give options - no open ended questions to start with. It also takes a lot of time, but it’s worth it. This has been a game changer for us.
I mentioned the Squirrel Scouts - this has been the biggest game changer. This is about mixing with similar aged children in an environment where there is no pressure to speak. Suddenly the speech has started to come. Can you find something similar? It doesn’t have to be the Squirrel Scouts, but something where there is low pressure, fun, similar aged kids and actions are rewarded rather than talking.
Read, read and read some more. And talk all the time, narrate your day. Ask your child questions as you normally would and wait as if expecting an answer when it’s their turn, if they don’t say anything after 5-10 seconds just carry on with the next part of the conversation and one day they might suddenly say something in the gaps.
Ask questions to the teddy bear e.g. Hello teddy bear, I wonder how Fred’s day went? Or, I’m not too sure what Fred wants for a drink, do you know teddy bear? This can encourage them to laugh at you and suddenly give an answer.
When they do speak. Don’t act surprised or shocked or give any indication they have done something unusual. This feels really strange. But just carry on as if it’s the most normal thing in the world that they have just done.
Lastly, don’t reward/punish the speech. I.e don’t say things like - You can’t have a biscuit unless you say X. This is counter productive and encourages silence. The other way, - I will give you a sicker for every word you say today. This only internalises that speech gets things and when you stop giving things the speaking stops.
Feel like I’ve bombarded you there, but hopefully some of that is useful to you.