bleeding after sex?

Dani • Married to the love of my life. TTC our first.
My husband has average sized junk. My doctor told me I have petite anatomy. Whenever we have sex my husband goes really gentle, yet I always spot pink blood for a little bit after sex. I've been to my doctor and he told me all my bits are normal and fine. Anyone else experience this? Anyway to stop it or does anyone at least know why it happens?