Macbook pro retina 13 (late 2013) battery life problems

I bought my laptop last summer and I have been having issues with battery life recently.

I used to be able to get around 7-8 hours of battery life with light use (MS word, PDF viewer, and some web browsing), now I only get around 4 hour max of battery life with similar use. My macbook overheats every time I watch some online videos or movies.

Activity monitor shows that chrome has the highest energy impact, but I have been using google chrome since I bought this laptop and I don't think it's causing the problem. I also switched to using Safari to see if it fixes the problem, and it didn't.

I really have no idea what is causing this low battery life/overheating problem. I think it all started around the time I upgraded my computer to OS X Yosemite.

Can anybody help me figure out this problem please?