Good games and bad games?

I was playing against a chess champion in highschool the other day, and we've played many games. He comes from a small highschool, but it's big into chess. He's played in state and national tournaments, even against Chinese foriegn kids. At first he beat me, then we started beating each other, and win-loss ration was about the same, but the past three games I've destroyed him. My opening and mid-game are very strong, and I would take 4-6 powerpieces out for the loss of maybe 1-3 of my own, and the first game I almost took out 5-6 of his powerpieces for 1-2 of my own, and the last game I had at the midgame 3-5 more powerpieces than him. He plays a strong end-game, and it narrowed towards the end, but I still beat him.

My strategy is to deploy my peices towards the center quickly, create a battery or two, that's opening, and than the midgame is destroy every and all peices I can, and than once that is achived, go for the checkmate. I think I could do better if I balanced destroying peices and getting my enemy checkmate.

Then I played against a guy who's 50's or 60's played for many many years, once part of the USCF and won a few small tornuments, and I did very bad. I made a blunder with my queen early, where he did a skewer, and I gave up soon after. Hurt my confidence, and now I don't know if chess is my thing or if I'm good. When I first played him I lost usually. Then we stopped playing, and I fine tuned my skills, and when I played him again, the first game, I destroyed him. Now he's won the past few. What do you think my Elo rating is? My first one was around 1,000-1,400 I'd approximate.