I'm confused

I'm 17 days late I keep getting all the symptoms that I'm pregnant I had unprotected sex last Wednesday and took the morning after pill the Friday but for a week I've been feeling really sick, my headaches have started coming back from when I was last pregnant but I'm confused because as I said above I last had unprotected sex last Wednesday but before that I hadn't had sex full stop since the day I conceived my daughter jan 2017 does anyone have an idea why I'm so late and getting these symptoms anything that would help I can't be pregnant again I've a lot going on with home life I barely have time to look after myself I put my mum and child first and forget about myself as my mum's really poorly and needs me 24/7 someone help please