Pompey had to patch together a side for their FA Youth Cup second round clash with Bromley at Fratton Park.
But despite taking the lead through another goal for the prolific Harry Anderson, they were knocked out of the competition.
Liam Vincent soon levelled for the Londoners and, with extra-time looming, Ben Krauhaus grabbed their winner.
And Daish admitted that his inexperienced side missed several of their older players, such as Harvey Rew and Charlie Bell.
The professional development phase coach said: “I’m really disappointed for them. I looked at the injuries and suspensions and wondered whether it was going to be our night.
“Take the winning goal, when our strongest header of the ball was taken out and the referee tells him he can’t come back on the pitch.
"That team and the bench was built up with first year scholars and members of the under-16 side, while Harry Anderson had a late fitness test."
“Good luck to Bromley and we just have to take it on the chin, but some of the performances out there were really positive.
“That team and the bench was built up with first year scholars and members of the under-16 side, while Harry Anderson had a late fitness test.
“He had a groin problem and I’m surprised he lasted the 90 minutes, while Harvey and Charlie are massive players for us and were missing.
“I can’t fault the commitment of our side and if we’d managed to get that second goal, I think it would have changed things.
“You’ve got to give Bromley credit for sticking in there and when they got their chance at the end, they took it.
“But we’d been waiting for this fixture for the past six weeks and couldn’t play it when we had a full squad. Perhaps it wasn’t meant to be.”
The squad will have a three-week break following Saturday’s trip to Exeter in the Youth Alliance League.
Daish: “I think everyone needs the rest – players and staff. I’ve been really pleased with our performances and application in the first half of the season.
“We’ve shown some resilience to keep things going as normal as possible and now need a bit of a breather.”