At 11 weeks with an average pregnancy with a single baby, you should be able to feel the top of the uterus about slightly less than halfway up between your pelvic bone and your belly button.
There is no mistaking the feel of the uterus, as it usually has a somewhat "hard" feeling to it. You can best feel it by lying on your back and then gently pressing down to feel between your belly button and pubic bone.
At 11 weeks your uterus should be just poking above the pubic bone. But remember, this is an AVERAGE. All bodies are different and all grow at a different rate. I could not feel mine at 11 weeks, but at 12 weeks I could. It feels like a soft ball.