Wifi works for my entire family, but not for me? Have an iPhone 6

My mother has a 5s and the wifi works fine for her, my sister has a iPhone 6 and wifi works fine for her. But with my iPhone 6, it says I am connected to wifi, but whenever I use safari or Instagram or any kind of app- it says no internet connectivity. iMessage works, but very slowly. I have tried rebooting the wifi, but I don't think its something wrong with my wifi because it works fine for everyone else. I often have problems with every single wifi I connect too, when I am on LTE it works fine but it took up all our data and got my data turned off. I really need to have this wifi work. Anyone have an idea?