Hi Louise,
My KC was diagnosed when I was 17 after a particularly visceous game of rugby where I left with two extremely swollen and black eyes. I have had it for 20 years now. For me it was quite aggressive which menat I had to give up motor racing within a year of strating. I had my frist graft as soon as my A levels ended and my second a year later. Only about 10% of people with KC ever get to this point so what Iw ent through was quite unusual. This was because 20 years ago, there was not a contact lens that would stay in my eye.
In 2004 again within a year after starting to race comeptitivly, while in Germany I found the night race extremely ahrd and on my return found I had KC in my right eye in the cornea the graft was attached to. It hads now been stabel for 2 years and being in my late 30's I hope it stays that way.
I swim with contact lenses after finding some great goggles for water sports and they surfice while swimming. I am at work at the moment and the filth filter prevents me from looking up the goggles I use, why only IT knows, but I will post the link tonight.
Due to the irregular astigamtism we have, the benefit from glasses as you have found is limited. COntact lenses give us a proper curvature of the cornea and tears filling in all th iregularities between the lens and the cornea. They are uncomfortable to wear but with minor adjustments to lenses or work/home environment I have pain free lens wear and the same quality of life. There are a small range of soft lenses for KC too.
KC is evry unpredicatable and I have no reason to contradict what you have read. From my personal experience the progression of KC is slower in later years, as I said mine has been satble for over 2 years now.
Even without lenses I found swimming fine, I found the roped off lanes easier because I could see the edge of the lane and go in a straight line. So I knew where the end was I used to count the number of white stripes I passed. The pool I go to rope off a few lanes and they alternate red and white so I had an indication of when I was nearing the end. As to how useful this would be when competing I think only yopu will be able to do that
Since joining this group and asking the silliest of questions I have since learnt how to do all the things I could do before the KC set in so vision and limited vision cause no problems at all in my life. The only thing I can not do is race cars as the lenses I have are banned under MSA and FIA regualtions so I compete in competitions on how clean is my car. Have a look in the hit Chat area where I have boasted about my sucess

I wear my lenses to get to the competition, take them out, clean the car and wait for the result. Then put my lenses in again so I can drive home.
Ask loads of questions even if you think they are daft, when you are down have a good old moan and you will find one of us here to hopefully offer a helping hand or a shoulder to cry on plus we share the good times too.