Chris Wood's successful 63rd-minute effort followed by Glenn Murray's strike eight minutes later kept Gus Poyet's men firmly on course for promotion.
Rovers, three points above the drop zone, have now not won in seven games, but Parry believes another three or four wins should see them safe.
He said: "We've got 11 games left and we're quite capable of getting another three or four wins. Brighton's penalty looked a bit harsh but the referee gave it and up to then our game plan had worked to a tee.
"It is disappointing because our players worked their socks off and it's just not possible to give out any stick after a game like this.
"Brighton are a good side. You don't get eight points clear for nothing and even at 0-0 they didn't panic. It would have been the same had the game been scoreless with five minutes to play."