I get it, it feels too final, however.. Your mum would likely be devastated that you’re not part of her last goodbye and there to be comforted by everyone showing their last respects and love for her. A funeral feels final, however, it’s a momentous occasion of love and support, that’s why they’re so important culturally for most.
You will have everyone around you that day, rather than no one. It’s going to happen, think about when the day comes and what you will do if you don’t go, how you will feel etc.
You don’t have to conform to the norms; wear black, go to the actual ceremony (you could just go to the wake), go in the car with loved ones (make your own way there).
Grief does funny things to folk, but put yourself in the position; it’s Thursday and you don’t go, knowing everyone is there to show so much love to your lovely mum, you and your family and you missed it and all the support people are offering, how would you feel?
My sincere condolences