Sippy cup?

I ordered some NUK sippy cups for my 9 month old. They say 6 months + & I was hesitant on starting sippy cups because I thought the flow was faster.

Well I gave my daughters milk in her sippy last night since the pediatrician recommends we start & she loves to hold it cause it has handles, but she gets nothing! The milk seriously comes out so slow she gets mad & it took her 10 minutes to drink an ounce ! What the hell lol I thought sippys were more advanced?