The Bulls almost snatched a vital three points in injury time when Nicky Featherstone hit the post from 20 yards.
Macclesfield sink to the foot of the table after their defeat at Bradford, while Hereford are two points adrift of safety with as many games remaining.
"I don't think it's going to be decided next week and if we go into the last game of the season, the fate will be in our own hands," said O'Kelly.
"If the players show the same work rate, commitment and togetherness we could be in with a shout.
"Our performance in the second half was more fitting with what the players have been doing on the training ground, but our first half was dire to be honest."
