Is it normal to

Lucky you. She has strong pelvic floor muscles, either because she's young, or because she's spent a lot of time deliberately exercising them.

If you both learn Morse Code, you could send each other secret messages by her clenching her vagina, and you tensing the same muscle you use to stop urination. Never know when this might come in handy.

my wife is a multiple cummer and squeezes very hard and is loud.

My guys love it when I do it. They get to hear my screams, and feel my pussy squeeze their cocks. Not all women do have those contractions. You're a lucky guy.

you must be in heaven!