It won't fit!

I bought a rabbit vibrator. Its head is about the width of three fingers?? (I have small hands).

Last night I tried it on myself and it doesn't fit! It hurts! Btw, I tried stimulating my clit, my nipples, I used lube... but the head really wouldn't fit inside me.

Can anyone tell me what's wrong? Any advise? I really want to experience my rabbit. Please help, and thanks!