If your child has a speech delay, that is.

Awhile ago i posted about my then 16mo DD not talking much. She has improved to what she was then, but from what i've seen with alot of other kids her age, she's quite abit behind, and now it's starting to worry me abit (I will be talking to her daycare about it on monday, who can bring in specialists and stuff to assess her, but she only goes 1 day a week, so i'm not sure how much use it will be?) It wasn't worrying me much before because she can understand ALOT more than she can speak, but she just wont talk. she will only talk when SHE wants to, and thats often very limited.

She can say things, but often not very clearly, she says things like "let's go" but if you don't know what she's saying, you might not be able to make out what she's saying ITMS?
she says things like "tee" for custard (DH called it custy occasionally, lol) and she does say mama, daddy, nana, but often not in context. she does know who we are, but she often wont say it to us, just babbling.
she says thankyou, but not when you ask her to say it (i.e. when she's taking something from us, but she will say it at the shops after i say thankyou to someone) she waves hi and bye rather than saying it.
she can tell me what a cow says (moo), what a lion says (roar) and a dog (woof) but its often with a fair bit of prompting, and sometimes she won't do it at all.
Occasionally she will repeat things i say, like the other day she took out some long life milk from the cupboard and i said "that's milk, Ayva, say milk?" and she said "mill" she's often dropping off bits of words that are trickier to say and often the words can be tricky to understand.

She can say probably somewhere around 30 words, but i know she understands ALOT. she can follow commands very easily, and is very mechanically minded (in that she can easily figure out how to do things, and how things work, and is very capable physically WRT things like climbing and "doing" things) but she is also very stubborn. she didn't walk at all or even attempt to take any steps until she was 11.5mos old and then took 8 steps and continued walking ever since.

sorry this post it abit everywhere, but i'm just getting myself worked up abit with worry, and i'm not really sure what i can do to help, or if she does even have a speech delay, y'know?