There is no income requirement for spousal sponsorship, however you will need to prove how you intend to cover the costs of living for you and your spouse once you return to Canada.
For the work you have been doing as long as you include an explanation about it, you should be fine. Get a few receipts and or make a "log" so to speak of all revenue generated from what you do. It is ok if the amount varies from month to month. I do not want to assume, so will just recommend that you make sure you are legally permitted to earn money in the country you are in.
If you have done any job searches, contacted potential employers ect. Make sure you tell/show them that in your application. Maybe you already have a job offer, if so, include a letter of employment or some tangible proof.
You will also need to prove your intent to return to Canada. You can do that easily as well. Include a letter from family/friends should you be planning to stay with them upon return, or rental agreement/lease if you have made arrangements of such. Anything that pertains to employment and or education (for yourself, spouse and or if you have children).
Take Care
MadeInCanada