K.R.
This may not be true in your case, but my 12mo old throws food/cup from high chair when she doesn't want it anymore. I might give it back to her once, but after that, she doesn't get it back. I firmly tell her not to do it, and if I can see it coming block her arm, but I don't make too big of a deal.
I would also suggest signing--but you have to be patient with it. If you consistently say & sign the more crucial words, she will 1st recognize them and either show a positive or negative response, and then you can help her sign (move her hands for her) as you say them, and one day she'll surprise you by doing one on her own. I sign "eat/hungry" "drink" "more" "all done". I have also tried to teach her nodding head and please.
Don't think you are doing anything wrong--you are obviously not b/c you have put so much effort and thought into your actions.
Congrats on natural conception--I too am prego naturally after fertility treatments with #1, and also conceived while breastfeeding...