Please go to https://www.irs.gov/coronavirus-tax-relief-and-economic-impact-payments for more information regarding your stimulus payment.  

The link provided does not answer my question about my situation. Can someone please help and answer my question? Do I have to amend/change my already filed 2019 taxes to “independent” in order to get my $1,200 stimulus check?

If your mother has already filed you as a dependent for 2019, then there is not much you could do. Any attempt by you to file an individual return now will get rejected by the IRS. You may want to have your mother amend her taxes which will take another 12 to 15 weeks to get processed as she will now be mailing her return. After, you could then file your own individual return. I know that defeats the purpose but that's the complication of amending and you refiling.