Substitute Ebony Salmon fired in on the break 14 minutes from time to hand the Robins a precious Barclays FA Women's Super League win.
Tejedor was happy with a first-half display in which her side created a host of openings but that pressure subsided, particularly after the goal, without Blues finding the net.
"It was really disappointing," said Tejedor.
"During the first half we had control and many opportunities to score, we played quite well but could not keep it going in the second half.
"We had done a very good high press in the first half and then went a little bit deeper. When they made the substitution and brought on the player who scored, she was really fast and we went deeper again.
"After they scored we almost did not play any more, the match stopped all the time.
"Very clearly it is goals we are missing and people who are able to score goals.
"We create good opportunities and build up from the back, we can travel from the first third into midfield and even reach finishing positions quite well.
"It is not that we don't produce chances, we do, but we do not finish them."
Tejedor acknowledged suspended England international Lucy Staniforth had been missed "a lot", adding: "We don't know what would have happened, it is too easy to say it would have been different but I never like to miss her."
Blues now head into the international break, a three-week period Tejedor would have preferred to play in.
"When you have such a bad feeling, you are looking forward to playing again and being able to change it," she added.
"Three weeks with this feeling will not help me, I would prefer to play right now."