Barca broke the women's attendance record as 91,553 fans watched them come from behind to beat rivals Madrid 5-2.
Ouahabi came on as a second half substitute in the Camp Nou in what she described as a 'special experience'.
She’s now relishing Sunday’s 12:30 encounter with United at the Etihad Stadium.
She said: "It was a great, very beautiful and special experience, especially because seeing the stadium full with all your fans and knowing that people were going to come and fill the stadium it was amazing.
"Those kinds of experiences are the ones that make you grow up and gain a bit of sporting maturity also. I think they are positive experiences and I hope they help me to make the team feel good in a situation.
BARCLAYS WSL ETIHAD DERBY: GET YOUR TICKETS
"The whole team is going to be plugged in and looking forward to it, because in the end playing at home in a stadium like the Etihad is going to be amazing."
Ouahabi is expecting a 'very exciting, very competitive' clash with United on Sunday, which will be played out in front of over 40,000 supporters.
Our 29-year-old wing-back, who won every trophy on offer during an 11-year spell with the Catalan giants, says competitiveness levels will be at '200%' as City look to see off United and move level on points with them in the Barclays Women’s Super League.
She added: "Derbies are derbies, right? They are very competitive games.
"In the end, a derby is always special. They are very exciting matches in which the competitiveness is 200%. And they have told me that these are matches in which the players are very eager to face the duels and the competitiveness that exists is very, very important.
"I hope this will be a very exciting game, very competitive because United are very dynamic, they have very good players and I think it will be a very nice game to watch and a very nice game to play.
"They are games that you enjoy and I think that people will also enjoy watching it."
But what would it mean for Ouahabi to earn bragging rights come Sunday PM.
She added: "Well, it’s another goal. I haven't been here at City for long, but I know what a derby means.
"I am very excited to be able to play this game, and to be able to share it with my team-mates and, of course, having the chance of winning it.
"The rivalry that exists between both wo teams is huge and I think that it generates a tickle inside any player, for being super excited for games like this."
CITY V UNITED: ETIHAD DERBY
City welcome Manchester United to the Etihad Stadium on Sunday 11 December.
Kick-off is scheduled for 12:30 (UK), with tickets selling fast for our third-ever women's match at the Etihad.
We hosted Everton there back in May 2014, before welcoming our local rivals in September 2019, when Caroline Weir’s wonder strike saw us run out 1-0 winners in front of what was then a WSL record crowd, and what remains a club record of 31, 213 fans.
With over 40,000 tickets already sold, it promises to be another historic occasion.
You can secure your tickets online by visiting: www.mancity.com/tickets/womens or by calling: +44 (0)161 444 1894.