The 19th Georgia was only in Archer's brigade through 1862. In early 1863 they were transferred to Colquitt's Georgia Brigade which they served with throughout the rest of the war.
Think I remember you said you've already read John J. Fox's regimental history of the 35th Georgia.
Both regiments are also in
Heroes in Martyrs of Georgia by James M. Folsom, which was compiled near the end of the war, the officers and commanders from a number of Georgia regiments in the Army of Northern Virginia authoring a history of their regiment up to that time. It can be read online at Internet Archive.org.
Here's the link to the history of the 19th Georgia:
https://archive.org/stream/heroesmartyrsofg00fols#page/32/mode/2up
History of the 35th Georgia:
https://archive.org/stream/heroesmartyrsofg00fols#page/136/mode/2up
History of Thomas's Georgia Brigade:
https://archive.org/stream/heroesmartyrsofg00fols#page/114/mode/2up