Hi Suzie,
What a beautiful, beautiful epitaph, farewell and/or tribute for your little boy. Far too beautiful to 'play around with' but much too important to leave imperfect in any way. I think the rhythm you have chosen suits it wonderfully and I hesitate to touch it, but I'll point out the couple of lines which just missed that ideal scanning. Actually, they wouldn't matter at all except that the rest of the poem scans so well, which makes them stand out and interrupt the flow a little:
I held you in my arms that morn,
When away from me you had been torn,
These are the first two lines and the first line sets up the rhythm. This second one 'almost' scans, but you have to read the 'When away' rather quickly to 'fix it'. I wonder whether you'd contemplate something like:
I held you in my arms that morn,
As from this earth you had been torn ...
Or
When from my heart you had been torn ...
or something like that. Can you hear the difference in rhythm?
I laid you down upon your bed,
Tenderly caressed your little head,
This second line has the same problem - just one syllable too many. You could say 'And tenderly caressed your head' but the 'little' seems somehow quite important to me. I was thinking something like 'I laid you down upon your bed, Caressed and kissed your little head' ? What do you think?
They came with haste and took you away,
A piece of me died too that day,
In the first line, perhaps you could put a comma instead of 'and', so the syllable count is the same but no meaning is lost
I could not accept what God had done,
I love you, Robert, my first born son.
This last line is so, so important that the line preceding it needs to be just right, too. The meaning is clear but again there is one syllable too many for it to be 'perfect'! I've thought and thought and can't reword this in exactly the same way using 'accept' - if only there was a single-syllable word for this! The best I can suggest is something a little stronger and using a little poetic licence, e.g. 'What cruel deed my/this/our God has/had done! I love you, ...'
It's very sensitive and very beautiful so I hope you don't mind my commenting on something that is obviously very precious. Please feel free to ignore all these comments since I AM nitpicking, not being critical.
I hope I never have to put tears on paper, as you have,
Symphony