Assuming that your chart calculations are correct and that the '2 minutes' you refer to is time, then your Ascendant is somewhere around 29 and a half degrees Libra on your calculations. If you were born earlier than this time then you will be Libra, however the next two minutes take you into Scorpio.
In practice it isn't easy to come up with an answer to this one, even for a professional. - you could try pressing her for more precision to narrow the range but if it's quite narrow to start with, I doubt this will be useful.
There are arguments about the transitions between signs, many Astrologers will argue that for the Ascendant you are either Libra or Scorpio but not a mixture of both. There's a minority view that there isn't a sharp change at ingress but a smoother change over four or five degrees, which is likely to mean that you have a fair Scorpio influence.
There are a number of methods open to a professional to 'rectify' the birth time - these are usually related to the timings of major events in your later life, such as the year you got married or went to University, or got picked for the local Sports team, etc. However you will probably get ten different 'rectified' birth times from ten different professionals - it just isn't that precise.
So unless your mother's memory suddenly improves, I think you have to take yourself as 'cuspal'.