Re: had to wean at 18 months...
Congratulations on making it to 18 months! That's a terrific achievement. I'm sorry breastfeeding had to end early, especially because cold turkey weaning tends to result in exactly the types of problems you're experiencing: engorgement, leaking, discomfort. Sometimes even mastitis.
How long it will be before your body decides to cut production down to a more tolerable level, or to nothing, is very hard to say because the answer is unique to you as an individual. It could be days, it could be weeks. The longer you put up with the discomfort and fullness, the faster the process should happen. But don't be afraid to use the pump to remove the minimum amount necessary to relieve the discomfort. Taking the edge off should not prevent your supply from decreasing, albeit at a slower rate than if you just put up with the fullness.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"