I can’t cum???

I’m a 21 year old girl in a relationship with another girl, I’ve never had this issue before until recent and it’s starting to upset my partner.

During sex I can reach orgasm and ready to cum (I’m a squirter), however recently I’ve reached the orgasm but physically struggle to cum but my partner says she can literally feel it in me that I have reached orgasm.

It’s obviously a big thing from going to squirting all the time to struggling to finish! I would carry on with the sex until I finish but it starts to get uncomfortable for me.

I don’t know whether it’s because I’ve started to over think it since the first time it happened or there’s a genuine issue?