Hi

I was going through some documents today and discovered 4 invoices to a CC company for services rendered. This is dated for 2006.
At the time I did the work and traded under a company name but it was just me doing some work after hours. The plan was that I would have registered as a sole proprietor and go on from there.
I only did the 6 jobs for the same company and then decided to not go into business. The amount was roughly R22 000.
At the end of that year I filed my returns.

Now for my problem.
I can't for the life of me remember if I declared those 4 amounts on my return form. This was before eFiling so I can't check my records.

3 questions.
1.) Can I find out if I had filed this somehow?
2.) What do I do if it turns out that I forgot?
3.) What penalties do I face if it turns out I didn't file these?

I seriously hope I can stop at question 1.) and I actually did the returns.

I know this was a stupid oversight on my part but I'm really worried.