Dellin Betances would prefer to be doing more than throwing bullpen sessions, but the right-handed reliever understands this is part of the process after not developing enough arm strength in spring training due to a right shoulder impingement.

“I never really got going in spring training facing hitters,’’ Betances said after throwing 25 pitches (five breaking balls) during a bullpen session at Yankee Stadium before Thursday’s game against the Red Sox was rained out. “I have another [pen session] on Sunday, maybe 30 pitches.’’

Boone watched Betances throw and laid out a plan for a very big part of the Yankees’ bullpen.

“He will probably throw one more bullpen in a couple of days. Assuming that goes well, he will probably go face hitters and do a [simulated] game or something,’’ manager Aaron Boone said. “That could be as early as when we go on the next trip.’’

James Paxton came through Wednesday’s start against the Padres with no problem in the left knee that landed him on the IL May 3 due to inflammation.

“No real issues, felt pretty good based on the game and the way I came in [Thursday],’’ said Paxton, who didn’t give up a hit or a run in four innings of a 7-0 Yankees victory. “Confident about getting back to 100 percent. It feels good.’’

Paxton said he wasn’t informed when his next start would be and the Yankees, who are off Monday, haven’t announced their rotation beyond Sunday night.