@Mr X
Salam bro,
I think you are worried about missing some crucial step/
rukan which you think is a must for funeral prayers. I don't think there any specific thing you should worry about.
The biggest thing your mother now needs is
maghfirah. For that, you can recite any part of the Quran, praise Allah using any famous supplication, etc. The most important thing is your demeanour.
Yes, it is a great loss, but you can also be grateful that your Mother had a wonderful life and had fewer ageing issues like illness. In the end, it is a test. Yes, you can mourn like Hz Yaqoob when he lost Hz Yusuf, or the Holy Prophet (SW) when he lost his son. It is totally alright.
Being sorrowful is emotional and is not an issue. Just, please do not be grief-stricken as such that it could hurt your spirituality or belief.
Lastly and most importantly, you can make a wow to change your life and ask Allah to grant your mother the highest place in Jannah, and you will always pray Asar etc and never miss that deliberately. You should also wow to feed the homeless monthly or so.
All these are to create a case so that Allah can forgive.