The
for loop is wrong: you don't want to cycle through all animations at once, you want to wait some time before the next frame is shown. By the way, it's cleaner not to mix input handling (
sf::Keyboard::isKeyPressed()) with drawing, and to encapsulate members (
GetSprite() returns a reference, which is questionable).
If you don't want to implement animations on your own, you can have a look at
Thor's Animation system. It provides some ready-to-use classes where you only have to specify attributes such as texture rect or animation length.