I have heard that your body absorbs what it needs and excretes the rest.
Sounds like you are doing a great job
You can never overdose on good, nutritious food, what your body does not need, it will get rid of. You are doing a great job, keep it up.
The body can get too much of certain vitamins, but I don't think 2 glasses of juice are too much. A,D, E, and K (ADEK) are the vitamins that one can get too much of. Most people don't have enough nutritients, so not enough is more common than too much. The rest like C, B's, etc. the body excretes. Do your own research about it or ask a qualified professional for more information. Vitamin D is very important and it is possible to have your levels checked. I think it is possible to check levels on the others also.
Vegetables are better than fruit, because fruit has a lot of sugar in it. Spinach, kale, leafy green veggies are some of the best. Garlic would be good to juice also. Carrots are great.