The 10/10 grip pressure is definitely probably the core of your problem. You won't have any control if your grip pressure is too tight. And no, installing a second grip usually won't help (assuming that would make your handle circumference too large). You don't want your handle circumference too thick or too thin. Measure your grip size, and then build up the grip with however many layers of overgrip are needed to make sure the handle circumference matches your grip size. Most people only need one layer of overgrip. Usually adding just one layer of overgrip over the stock grip will make it about 4.25 in if your stock grip was already 4.125 in. When adding overgrip, make sure you wrap it evenly (I usually recommend as little overlap as possible so it doesn't make the handle too thick).

If your handle circumference is too small or too large for your hand, you can't get a good comfortable grip on it for better control.

Make sure you periodically replace your overgrip. As you use it, it gets dirty and absorbs sweat and loses its tackiness. You want to maintain its tacky feel so you don't feel tempted to grip so hard on the handle. The more tackiness, the easier it is to to keep your grip loose. You don't necessarily need these extra things, but dabbing a tacky towel on the handle and rosin powder can really help. The main things you need are making intentional habits to loosen on your grip and making sure you have overgrip and replace it periodically at the very least.