Christina Rossetti's remember is a good piece of poetry https://www.poetryfoundation.org/poems-and-poets/poems/detail/45000 You could then go on to speak about a few anecdotes of when you remember you mum holding your hand and when you made each other smile.
one of my brothers is doing the order of service, so that should include me at some point. Can't say how i will feel on the day however, tearful perhaps?
I solely organised my dad's funeral in March but I knew I wouldn't be able to read during the service. My cousin read a sonnet that I had written and an uncle read the eulogy. I spent the whole service sobbing into a handkerchief.