You are doing a fair number of things right: Lightroom, raw and pumps off. If you shoot with a high aperture, you will lose detail due to diffraction. On my camera, a Nikon D800, I lose detail if I shoot above F8. But there are times when depth of field out weighs the loss.
For the best shots, a macro lens is what you want. Your stock lens looks pretty good by the way so it might not be a high priority. If you go that way, go with a focal length off around 100. Nikon and Canon have the best glass but at more $$$$. Tamron, Tokina, and Sigma all have good macro lenses that are rated just a touch lower and you might be able to get one used. I once got a used tele converter that was rated “ugly” because it had some scratches on the finish. But optically, it has been just fine.