Susan Ashley, in her book, "The ADD and ADHD Answer Book", states that 25 to 30% of children with AD/HD experience anxiety. So it would follow that it would also be present in adults with ADHD. Pretty good web site here on adult ADD - http://****.com/#/welcome/
The 120 mgs strattera does sound a bit high. Most sites I googled say that, "the dose may be increased to a maximum of 100 mg in patients who have not achieved an optimal response. There are no data that support increased effectiveness at higher doses."
There is always a "guess the dose" game going on since everybody has different levels of ADHD, different body sizes, etc. This is very common (and safe) for a doctor to do. But there are limits and it looks like it might be time to try another medication if 120mgs of strattera is not doing much for you. Hope this helps. Please post if you have any other questions or need more reference material.