Question about (USA) taxes: file under Schedule C or "Other Income" on Schedule 1, Line 8j?

After being laid off in IT at age 50, I started full-time in my small business (martial arts instruction) last year and also started doing surveys and studies to supplement. At tax time my H&R Block guy filled out 2 Schedule C's, which means I had to pay self employment tax on all earnings plus he charged me for the second Schedule C which significantly upped my tax prep fee.

However, based on the IRS definition of a business could I just file it under "other income"?

I don't incur expenses. I don't promote this as a business. I don't work regular hours. I barely logged on last month. I do try to make money, but thats the whole point right?

Last year I did make $12k and this year $15k. This was mostly on Prolific but I used other platforms also.

Though my business revenue is increasing each year, I still make as much as a fast food worker. This tax liability is nuts, as well as the tax prep fee.