Porter made a goalscoring return to the side following a loan spell at Chesterfield, holding his nerve to convert an 81st-minute penalty in the Blades' 3-2 first-round victory after earlier spurning a golden chance in front of goal from Tony McMahon's cross.
"I felt as though I'd let the lads down a bit with my miss," Porter told Blades' Player after the match. "Obviously that would have made it 3-1 and when they got the equaliser I was a bit devastated.
"So when I got that penalty chance I wasn't going to give it away easily. Jose (Baxter) was putting me under some pressure to get the ball off me, but it wasn't going to happen.
"I'm not going to lie, I was nervous after my miss, so I was glad to see it go in."
Porter hopes he can rekindle his partnership up front with Shaun Miller after playing alongside each other for the first time since December last year due to the latter's knee injury.
"We had an inkling we might start on Friday," Porter added. "We were both speaking about it and both excited to be playing alongside each other again.
"We agreed there were glimpses of what we had before he got injured and hopefully now we'll get a few more opportunities to show that before the end of the season."