In need of some clarification and help

[brizzlesticks]

First to make the answering more efficient I will provide background information before I pose my question.
I am an American citizen who came to the UK with my American Fiance' in August 13th, 2013 because she was attending the University of Edinburgh for a 1 year masters program. We were expecting difficulties at border control with regards to me accompanying her, but assured the border control we would be leaving in 4 months and returning home for the Christmas Holiday. He trusted what I said and stamped me in for 6 months with a special handwritten stamp (which I found to possibly be a person of interest stamp due to my unique situation). I held up my end of the bargain and we left the UK December 12th, 2013 to go home.
While home in December my fiance' was planning on returning in January. I found an internship that allowed me to apply for a tier 5 temporary worker visa. I applied and received the visa and came back to the UK January 20th. I went through border control smoothly without hassle. I have since left the country 3 times with ease upon returning.
Now to my issue.
My visa was only for 4 months (expires June 8th, I already have my plane ticket booked) but my fiance's program does not end until August and she will be staying here until then. As you can already tell where the question is going, I would obviously like to stay with her.
I have exhausted every route and definitely want to stay away from the illegal ways (overstaying, deceit, etc.) as it can affect future traveling.
I wanted to pose this question to see if anybody else had an idea as to how to make this happen? I cannot extend my current visa due to the fact that I cannot get a certificate of sponsorship so I cannot apply due to the points calculator.
Before I pack everything up and head home I wanted to give it one more shot.
If you have no ideas at all, thank you for your time reading this!
-Brady

[Casa]

If you delay your departure until the end of August you will be an overstayer. This will flag up for any future visa applications or entry into the UK.

[brizzlesticks]

@Casa, thank you for your reply. I think you may have missed in my original post "I have exhausted every route and definitely want to stay away from the illegal ways (overstaying, deceit, etc.) as it can affect future traveling."
I will not be doing anything illegal and know the consequences of said actions therefore I was hoping to gain the knowledge of untapped legal ways beyond extending my visa or re-entering as a general visitor if any such option exists beyond this.