Topped a few days ago. I’m planning to do a mainline technique for both of these girls. I did that with my last Humboldt Afghani grow and I ended up with the highest quality buds that I’ve grown so far, so I plan to stick with it. The planet of the grapes is thriving. The Blueberry muffin hasn't been quite as strong but I think she is going to be fine I just have to keep a close eye on her. More updates soon!
I'm kinda having same problem as you atm. What helped was getting a kitchen scale to weigh your medium bag dry then fully saturated and you deduce the water content for a small plant then you can do proper drybacks and maintenane shots as well as how much she transpires once they pick it up. Note that a standard 5Kg scale won't take more than a 2 gallon and you will probably have to make a stand to properly use the scale so check the scale capacity for your medium but if you can calculate water content you'll do better in a smaller bag.🙌