Must I pay Self Employment tax from doing part time RE

[Jason Smith]

In the midst of doing taxes this year my CPA says she feels that I need to file as Self Employed  because of the amount of time I spend doing RE.  I only do this part time and have a full time earned income job.  I flipped 1 house last year and added 2 rentals.  I am not trying to pull one over on the gov but filing this way will cut my refund in 1/2 as opposed to filing as capital gains and not SE.

So what are your feelings as to the best thing to do here?  What is actually required vs what is best practice?  How should I proceed?

thanks in advance