Jelly Making Question

Some of you seem to do a lot of canning and preserving, so I bring my jelly question to you. I've looked all over the Net and can't find a satisfactory answer.

I live in West Texas where the elevation is almost 3000' above sea level. My jellies seem to never gel quite enough. I finally figured out it is because I am dealing with mostly a liquid, and it doesn't get hot enough. I read that to gel at my altitude, the syrup needs to heat to at least 214 degrees (F). Well, liquids here boil at ~207-208....ergo, not hot enough to gel no matter how long I boil. I have read that at high altitudes you must add time to the processing time. I don't understand the science. The boiling water that heats the jars won't get hotter than 207-208 either. Will more time make the contents hotter than the boiling point? I would think one would have to have a pressure canner. Does this mean that it is impossible to make jelly here unless one has pressure equipment?

Help--I really want to make jelly that is the proper consistency.
Thanks ~ pen