Let's start by clarifying the core components for your design. You mentioned using an Arduino Mini, an SSD1315 LCD screen, and an EC12D1564402 for menu selection. To make sure we get the schematic right, I have one quick question:

Feel free to answer or let me know if you’d like to assume a standard variant, and then we can move on to the next details.

Great. For the rotary encoder (EC12D1564402), do you want to use the integrated push-button function in addition to the two rotation outputs? If yes, which Arduino digital pins would you prefer to assign for A, B, and the push-button signals (for example, pins D2, D3, and D4)?

Let's assign the rotary encoder signals as follows:

Do these pin assignments work for you?