How i can find out if he has Vasectomy?

Mea

We are trying to have a baby for 15 months and no luck on that.Doctor said everything is fine with me, but he gave me hormones to help, but still no luck. I asked my boyfriend if he is taking something like birth control or if he did Vasectomy, but he said no.

Can someone can tell me how I can find out if he has or not Vasectomy? I am really stress out about that. Please