You should be filing as Self-Employed reporting your income and expenses on the T2125 - Statement of Business Activities. When you file this way, you are still contributing to CPP, with the remittance being submitted with your tax return.
You are not eligible to claim for your meals using the "simplified method" of $17 per meal. This is only for employees in the transport industry. Self-employed persons can claim 50% of their meals and must have receipts to make this claim. (Note Long Haul truck drivers are eligible for 80% deduction).
A complete list of eligible business expenses can be found in this link to the CRA information: https://bit.ly/2EDc2vB