My Stats (just for Party Poker):

Stakes: .50$/1$ at Party Poker
Profit after 3,144 Hands: 187.18$ (+5.95BB/100 Hands)
Profit with one pair: -114.26$

If you are getting your information from the Poker Tracker Misc. Stats tab (as I did), you will notice that it includes <u>all</u> of your hands even the ones that you fold. So if you cold call a small or medium pair for 2 small bets preflop with 4 players sure to be in the raised pot (which you should), then fold it when the flop does not hit your hand -- that goes as a $1 loss. Same if on the small blind you have a pair of 2s and it is raised and reraised before you and you fold it is a $0.25 loss in the pair column. There is a box that you can click called "Show Only Hands That Were Not Folded" that will show what your results are hands you do not fold. For me all of the hands show a profit if I click this box. I wouldn't take this too far because it is <u>definitely</u> possible to fold too much thus showing a profit by clicking the box but being an overall loser because of a tendency to incorrectly fold in big pots. Don't fall into this trap! Call down if the pot is big!

As for the two hands you posted:

Hand 1 is played correctly, and on Hand 2, you probably should have raised on the flop against two players with your top pair to try and define SB's hand a little better (calls with AK, AQ, KQ versus re-raises with a big pair or AJ, for example) and to get more money in the pot from both players if they are on a draw (like they would be with AK or hearts). The turn bet is fine. On the river the King is a scare card with the preflop raiser still in so you might have considered a check/call line (but not necessarily check/ fold).

I wouldn't worry too much about a low (over even negative) win rate over 2500 hands. I just put up my win rate for my Party Poker play. My overall win rate at just under 10,000 hands is +2.19BB/100 Hands and in the middle of that I had a -100$ downswing over 2,259 hands while whoring bonuses at Stars and Paradise (none of the results included in this reply include the bonuses). I think the important thing is to continue playing tight and aggressive preflop and to continue to read and post here to keep fine tuning your post flop play. And remember folding in marginal or scary situations when the pot is big (and usually it's big at Party Poker) is generally wrong.