MacBook Air Freezes

I have a 2014 11inch MacBook Air, 1.4GHz Intel Core i5, 4GB 1600MHz DDR3, Intel HD Graphics 5000 1536MB, running on OS X Yosemite 10.10.5

My computer will randomly freeze. While surfing the web, editing photos, or watching videos. When I first bought the laptop I overloaded it with a ton of photos. I am a wedding photographer and, at the time, did not own an external (I do now). I assumed I pushed the computer to it's freezing point with how many photos I had and the editing programs I was (still am) using. I use Adobe Photoshop CC 2015 and Adobe Lightroom 5. The only way I was able to "fix" it when it froze was to press the power button until it shut down.

I now have all of my photos on my external and figured out how to see what was taking up space (About This Mac > Storage). However, it still freezes at least once or twice a week.

I have tried deleting items and cleaning up my storage area. when editing photos I only edit and then I immediately transfer them to my storage because I am fearful this is a majority of why there is an issue.

Other major programs (I think they're major?) that I have are:

Microsoft Office 2011

Showit (designing/editing my website)

WHCC (ordering prints and products)

Thoughts?