Is there a way, being self employed and 70.5, that I can contribute to a retirement plan?

Unfortunately, if you were 70.5 or older on 12/31/18, you are not eligible to make a Traditional IRA Contribution. 

Thank you! What about SEP IRAs or personal 401ks

You can still make contributions to a SEP IRA or a Solo 401(k) if you are reporting a profit on your Sch C.  Keep in mind, you are required to begin Required Minimum Distributions (RMDs) from these accounts by April 1 of the year you turn age 70.5.

Thank you very much