Painful sex

Just wondering if anyone has had any experience with tearing during sex? I've only had sex with my current boyfriend and every time we do I get a small tear - like a paper cut - at the bottom of my vagina.
It's quite painful and makes sex awkward and insertion very uncomfortable. 
We always do A LOT of foreplay, use lots of lube and take things really slow so just wondering if anyone has experience with this and any advice to offer?!