If you are going to shoot at f/1.8... you have to know that is going to let in a ton of light through the aperture and into the sensor.
Last year when I shot football with my 60D, I was shooting at f/2.8 (which is about 2.3x less light than at f/1.
I was getting shutter speeds of about 1/6000 and some at 1/8000 of a second.
So I don't know if yesterday was cloudy and today was sunny, but that what you are looking at.
Since you are in the early phases of having the camera, I'd suggest shooting in aperture priority, setting the exposure compensation in the middle and allow the camera to choose the shutter speed. If it was sunny, I'd probably set the iso to 100.... Then half press your shutter and look and see what your shutter speed is. It should be at least 1/(focal length), so if you shooting at 100mm, then you should at least have 1/100 of a second.