Yes, you still need to claim your income that you were paid by your employer. If the company had other staff or owners, you should check with them to see how you can get your T4 (or other) slip, if you didn’t already get one.
I already did my taxes for last year without using work income. What do I do now to fix it
Send in a request to amend your tax return for the appropriate year. You should wait until you have rec'd the NOA.
You may be able to do it through your online account - there is a section for 'change my return.'
I never did receive a NOA. Who and where do I ask for an amendment
Do you have an online tax account with CRA? If so, sign in there. You will see the NOA if it was produced.
What tax year are you working on? It must be 2018, if you just filed in November, so it should have been assessed by now.
There should also be a place there to 'change return'. It will either let you file it online, or tell you what you need to do.
If you don't have an online account with CRA, get one, it will make life easier. In the meantime, you could go to the tax website and search for the info needed. Sorry, I'm busy trying to d/l my stupid 2019 TT, which isn't working, so haven't got the website open.