Q: Have to turn wifi off then back on to get a strong full signal macbook

I have a macbook pro 15" retina. I am a photographer and have to upload images at the end of every day. I noticed that the internet speed was flucuating a lot. From like 3 mbps to 30 mbps. I thought it was the internet service at first, but then noticed if I turned off the wifi on my macbook, then turned it back on, I would get a full strong signal. It would then start to slow down again to a crawl.

I was wondering, anyone else have this issue? and is there a fix? Is it the macbook or maybe a Apple Express Airport update?

Thank you for any help, it is greatly appreciated!