Natalie McGarry, 40, said she was shocked at the rise in demand for T-shirts, mugs and banners during the post-referendum period.
The former Glasgow East MP is standing trial at Glasgow Sheriff Court accused of embezzling £21,000 while treasurer for Women for Independence (WFI) between April 23 2013 and November 30 2015.
A second charge alleges she took £4,662 between April 9 2014 and August 10 2015 when she was treasurer, secretary and convener of the Glasgow Regional Association (GRA) of the SNP.
McGarry, of Clarkston, denies both charges.
The court heard that the demand for supplies, merchandise and banners exceeded what the group had ordered - even after the referendum.
Dozens of requests for merchandise were coming in across the country and were directed to McGarry's personal email address.
The court was shown email records from Kathleen Caskie, then a paid employee at WFI, instructing local groups to contact McGarry directly for merchandise inquires.
And, in February 2015, an email was sent to members of the pro-independence group asking if anyone could take over merchandise responsibility from McGarry.
Defence solicitor, Allan Macleod, asked McGarry if she knew how many local WFI groups there were.
McGarry said she did not know the exact number, however, she said there was a "phenomenal" demand, as the court was shown records of 24 events organised by local groups between mid-February and the end of March 2015.
An emotional McGarry became tearful in court as she recounted the busy period.
She said: "I feel a bit vindicated by seeing this in black and white because people (giving evidence) said there wasn't much happening after the referendum."
When asked by Mr Macleod if she had asked for help, she said: "Yes, I had.
"It was overwhelming. I was out every day campaigning and trying to fit Women for Independence around my campaign."
The court also heard that McGarry was reimbursing some members for travel expenses with WFI funds, however, this was not declared to the rest of the group to protect members who were not in a comfortable financial position.
The trial, before Sheriff Tom Hughes, continues.