TMI but i need advice, please read

Okay so this is kinda gross but whatever. My bf likes to finish inside of me when we have sex (I’m on birth control and we’re both clean) and lately when I stand up or even move slightly to grab a towel to wipe off with, the cum just falls out of me. It just recently started happening and I get really embarrassed by it especially when we’re at his house and it gets on his bed or carpet or something. Is there something I can do to avoid this happening?? I try to squeeze as much as I can to prevent it but it still happens ugh!! I also do kegals whenever I think about them but that doesn’t seem to do anything...Help!