The only thing you can do really is keep bombing them. Use the heaviest poundage you can handle. Leg presses are especially good for building mass. I believe running hinders gains but there may be some here that disagree.

For tall skinny guys like yourself you need to cut down your exercise to just 3 main lifts--squats, deads and bench--work on impeccable form and consistently bring the weight up. Week after week you should get stronger and your legs should grow--remember to consistently up your calories as well. I can't say for sure but you probably over train, under eat, and do not go nearly as heavy as you could. Form is everything--do not sacrifice form for higher weight--in order to build big legs you are going to have to go fairly heavy. If you get your lifting form in order, injuries can be avoided. And by all means do regular squats not smith machine squats--find a spotter it helps even if only on a psychological level


And calves require a bit more work--try this for calve raises---in the upward position hold for ten seconds each rep---your calves should be on fire--calves have dense muscle fibers and need fairly high reps to respond.

205 every week? Move it up man, try to get up 5lbs every week

you coould try higher rep ranges. I hear alot of people do well with 20 rep squats. maybe not every week but once or twice per month mixed in with your low rep work might trigger some growth.

i do high reps on leg press and leg curls and ride my bike a lot.
i'm 6'4 as well and it seems to be doing the trick.

i've dropped leg ext. and squats do to sport related knee injuries.