Plan B One-Step - Does the pill work if you only take half of it?

Can I still get pregnant if I didn’t really swallow the pill? I left it in my mouth to water down but taste a bit of it. It’s just a funny story I didn’t want my sister in law to see me drink it down so I act I didn’t take anything about time she left the room. The pill was water down in my mouth. Can I still get pregnant? Should I buy an other plan B?

If you don't have a regular period, I'd suggest you're going to need the other pill, Ulipristal Acetate (Ella).
Plan B works by delaying your ovulation. If you're already ovulating, then it can't do that.
Some think it works in other ways, but the Manufacturer only says that is possible, as it has not been proven.
Ella seems to work in more ways to prevent pregnancy, even if you are ovulating.
Half a dose will not be enough to prevent pregnancy, if Plan B works for you at all. It's less reliable than regular hormonal birth control, & is just simply worth a try, in an emergency.
I suggest getting the other pill from a doctor or drug store. That one has had less hormonal side effects for me, too. Perhaps it will also be better for you, if you do not like the side effects of Plan B.