17+6 need advice, in the UK!

I'm 17+6 but for the past few days I've been feeling like I need to pee a lot and when I do, it can feel like I'm gonna pee a huge amount but actually only pee a little bit. It doesn't hurt to pee, what hurts is afterwards the only way I can describe it is that my uterus hurts. 
I'm going to phone early pregnancy but they will treat me like an idiot (they usually do) so I'm unsure of how to explain it. I don't think I have a UTI just don't know how to word it that I don't sound stupid