Welcome to the site.
I am Dr. Kaushik and i believe i can help you with your problem.
I am sorry to learn about your condition and i empathize with you.
-- Well you see Derealisation is quite commonly associated with Anxiety disorders such as GAD , Panic disorder and even PTSD ( Post Traumatic Stress Disorder) , so answering your first question i will say that it is not unusual to have derealisation in varying degrees, in fact this on and off pattern is the most commonly seen pattern where derealisation is often accompanied or preceded by an anxiety condition.
-- Yes you can lead a productive life even when derealisation is not gone completely and the best way to achieve this is by seeking from your psychologist / counselor a special type of counseling / therapy called as CBT, which stands for Cognitive Behavioral Therapy , which is a therapy that teaches the likes of you some coping skills and strategies to endure derealisation without allowing it to effect your quality of life. So in your impending meet with the counselor please make sure to discuss this CBT and ask him to start you on it. CBT is a very flexible one on one interview counseling technique which spans over a course of 12-16 weeks , with once a week timed sessions. The benefits of this therapy over your GAD and Obsessional thinking and more importantly on Derealisation will be there for you to acknowledge and appreciate, so please do consider it.
-- Please kindly refrain yourself from applying other people's experiences upon yourself as the intensity and duration of derealisation grossly vary from person to person as different people have different levels of coping strategies and ploys therefore while some of them may endure derealisation quite well without compromising on their regular quality of life and productivity but others with poor level of coping abilities may just buckle under pressure and let the derealisation take over their life. You seem to be included in the former category people who can endure derealisation without letting it effect your life and you have done it before too but it is just that now you have begun to doubt yourself , please stop doing that you are a strong individual and keep yourself reminding of this and do not let doubt prevail over you and seek CBT to give you an emotional strength so as to counter your doubt of failing in countering against this problem..
-- The fact that you google for reassurance, this speaks about your inner fear and dilemma about letting derealisation win against your self resolve and taking away your precious life from you , so on this i will say that once you get your self confidence and emotional strength back on track via the help of above mentioned CBT therapy then from there on you shall not require to seek such reassurances.
So kindly do the needful as mentioned above and seek the best therapy that is most appropriate for your underlying condition/s.
I hope this helps.
Wish you all the best.
Please kindly leave a Positive rating if you are satisfied with the answer.
Thank you Dr. Kaushik, your words have helped me so much - I was crying as I read them, they have given me renewed hope that I will be just fine.
Already I feel more positive and I know I will beat this.
Just keep this faith and I am positive you will overcome this.