I am a 16-year-old boy and I have sex with my girlfriend. I pull my penis out of her vagina before orgasm. And we only have sex shortly after her period. Or shortly before her next period. Can she still get pregnant?

Yes your girlfriend can still get pregnant.
What you’re doing is called “coitus interruptus”.
That means interrupted sex.
But sperm can still get into the vagina.
Some sperm comes out of the penis before orgasm.
You won’t notice it.
You can’t prevent it.
This sperm can fertilise an egg.
And your girlfriend can get pregnant.

Ovulation often occurs midway between two periods.
But many women’s eggs mature at other times.
When did your girlfriend ovulate?
She won’t know exactly.
Many girls have very irregular periods.
Periods do not always come at the same intervals.

You can visit a gynaecologist together.
She/he can offer you advice on contraception.