Hi I'm 17 and I'm wondering if I could be pregnant if I got my period on June 16th and I last only 4 days well on the 20th my boyfriend and I decided to have unprotected sex and he checked before he put it in and he pulled out before he was going to and he had to masturbate to get himself to and my ovulation day is on the 30th so could I be pregnant I'm very worried?

What's he going to check for and how... did he use a microscope. Spermatozoa are microscopic single cell beasties. If he didn't he wasted his time...
And yours.
And how could you possibly know what day you ovulate on withoutkeeping a daily Basal temp chart for well over a year. Every woman does not ovulate on the same day of her cycle... and there are no obvios way to know when. And wherever you heard he has to finish to make you pregnant...stop going there for advice. He could do it the instant he touches you with it.

So long story short... yes you could get pregnant... but you have to be at least two weeks late for your period before you can test and expect a reliable result.

Pregnancy is always going to be a possibility when you have sex... some situations may make it more or less likely, but the possibility will be there.

The only sure way to not have a chance of pregnancy is to abstain from sex. The consistent use of effective birth control by both partners will lessen the odds, but pregnancy does sometimes still occur.

Best to hold off on getting too intimate, and take the chance of things going further than planned, if you don't want any worry of an unplanned pregnancy.

How did you determine ovulation? Did you check your basal temperature for 6 months - a year to determine when you ovulate, or are you relying on an app on your phone?

Fact is, any time there's penile penetration, pregnancy is possible. There's more than enough sperm in pre-ejaculate, which makes his penis slippery enough to insert, so is present when you're having sex, to get you pregnant.

So yes, you could be pregnant. Why? Because you had sex. Worse, you had unprotected sex, and that significantly increases the odds.

Now you'll have to wait and see.

Good luck.