Quick question

Me and my boyfriend had unpretected sex on the night when i started my birth control. And he didnt pull out and all of the sperm went in and none of it came out. And weve been doing the samething every weekend. Now we just had sex and almost all of it came out. Could i be pregnant. Note i started my birth control on the 30th of april and it is now may 12th. Any help of answering this question would be appreciated. Thanks.