UTI, will it ever go?!

I got a UTI on Saturday and was put on co-amoxiclav and it wasn’t working for me, felt sick, etc. So I got my GP to change it on Tuesday this week. I was put on cephalexin twice a day 500mg and I’ve taken it everyday no fail but its Saturday, still hurts and doesn’t feel like much improvement at all. I’ve never had a UTI last this long with medication but is it because I’m pregnant that it is harder to go? Please help :(