MacBook Air Problems

Hi my name is Brittany. I've had my 11" MacBook Air for almost a year and a half and have never had any problems with it before. Lately it has become very slow and tonight has gotten to the point where I can't watch videos on netflix, youtube, etc. or use FaceTime effectively. I have plenty of space available on my hard drive. I downloaded ClamXav from the app store and ran scans to see if there were any viruses on my computer; however, it came up with nothing. Any ideas on what's wrong and what I can do to fix it? I'm a college student so my ENTIRE academic life is on my computer!!!

Welcome to the forums.

For starters, please make sure you have a backup of some kind.
An external disk with a Time Machine backup, documents synced to Dropbox or one of many other solutions to keep your irreplaceable data safe.

Next, download and install Onyx, choose the one suitable for your Mac. You probably have Lion (10.7) or Mountain Lion (10.8).

Once installed go to the 'Automated' tab, tick everything and let it run.

See if that improves things.

If it doesn't please go to speedtest.net and run an Internet speed test and post back with your results. All the issues you've described are reliant on a robust connect and that test will give us an idea how your connection is performing.