Sounds pretty normal to me. The frustration tantrums kind of come with the territory. In those cases I will just keep pointing and pointing to things till I get it right and say the one word name as you go "cup?", "teddy?", "bowl?" etc.

I taught my 18 month old the sign for "more" a few months ago and he likes using that for "I want..." and then he points to whatever he wants. That seems to have avoided meltdowns for him.

Otherwise, with regards to expanding speech, just keep talking "You want cup? Oh! I want cup mummy. Here you are. Thank you mummy" etc etc, have conversations with yourself And extend on things she says, so when she says "Wee" you can reply "Wee! Down the slide!".