Excessive white mucous 'down there' after intercourse? (sorry for the tmi)?

So for the past month or so I find that, depending on how turned on I am, when my boyfriend pulls out after intercouse theres a white glob of mucous at the bottom of his penis that's collected there during sex. I know its me because I get REALLY wet during sex and I find white discharge on my panties afterwards. I've always had discharge, but never to this extent and it only seems to happen if he goes in really deep and I'm really turned on. I don't have thrush or any STI's but I am a little worried about this...Can anyone explain this? I'm 18