Here are some comments on your weighting at present.
According to my size, I should need more weight than you. I have instructed in pool sessions wearing both a 3mm shorty and a 3mm full suit, and wearing either wetsuit will increase my weighting needs compared to you. As an instructor, I wanted to be a little overweighted so that I could sink quickly if needed or stabilize a student if needed, so that is even more weight.
With the shorty, I used 6 pounds. With the full suit, I used 8. If I were looking for perfect weight in a 3mm shorty in freshwater, I would not use any weight.
I once had a student come to me fo the OW portion of his class. We would be diving in freshwater with 7mm suits. Anticipating that, he had insisted on doing his pool sessions (different instructor) with a 7mm suit so that he would have his weighting perfectly dialed in for the OW dives. Based on that, he insisted he needed 22 pounds. By the time his OW dives were done, he was diving with 10 pounds, and he was thrilled with the revelation of how much easier it was to dive that way.
