Do what your intuition tells you to. Personally, I've never had a clearing or cleansing from an attunement (from a treatment - yes, but not from an attunement).
Because I had already spent a lot of time in a quasi apprenticeship with my first RM (a very gifted woman who was very open and giving with her knowledge and information) I strongly felt that all I needed from a new RM (my first RM is on a sabbatical from teaching and practicing Reiki) was the formality of an attunement to the DKM. My intuition proved correct.
I listened to my heart - not the people who said I had to take both a level 3a and 3b class to be a Master/Teacher, and not to the people who - despite the fact that they knew nothing of me or my prior training - admonished that I needed to deeply consider why I wanted to teach Reiki and what my commitment to teaching would be. The result - two students last week and I've now been contacted by a third person about Level 1 training.
I just followed my intuition - I never set out to be a Reiki Teacher two weeks after my Master attunement - it just happened - they asked for the attunements and information so I figured it was a sign. The passing of attunements seemed like something natural that I'd been doing all my life. If you feel compelled to do the attunement and your mother is willing I say Attune away.
-WilyBoudiccea