Worried about 20 month old daughter saying some words wrong and having a hard time pronouncing b and p words. Is this normal?

So my 20 month can say a lot of words right(she says hi,no,yes,dog,go,hat,shoe,thanks,eat,night these are her most common words) and says some phrase like I got it or I go now or give me but I'm becoming worried about the words she can't say right. She says die instead of bye, moo instead of more, cheese instead of please(this one lead to me giving her cheese and her getting mad until i figured it out lol), instead of saying baby she says wah wah(like she's crying), she says go instead of up. Should I be worried or is this normal. Any way to help her say b and p correctly,those are the hardest for her to pronounce? Thanks! via /r/Parenting http://ift.tt/2jx49fU