Why am I so insensitive to Adderall XR and need a really large dose to feel the effect?

You will be ok.
Do not worry.
You gave your body too much one day and your body was expecting to feel the same again but next day you gave your brain less amount of med. It preserved the memory of the accidental high and was expecting the same feeling again.
This have happened to me.
At first I freaked out but made some innternet research which was véry helpful.
What I did was to stop the Adderall XR for two days, 48 hrs. drinking plenty of fluids including electrolite drinks like pedialite usually found in the baby food area at pharmacies or supermarkets.
Nourish your body very well with vitamins and supplements while you are on Adderall. This way your body keeps on cleansing itself avoiding the accumulation of Adderall in your system.
If you do not do this, Adderall traces remain in your body and will start to develop tolerance and will ask you to increase dose in order to feel good and that is the point where Adderall addiction starts.
I suffer from ADD and Narcolepsy taking a 60mg. dose of Adderall XR.
When I take my dose and feel sleepy afterwards, I know is time for a 2 to 3 days break from it.
In the meantime I use natural CNS stimulants to avoid whole days in bed.
They are weaker but they help.
I can not tell you what to take as complementary options but doing some internet research will give you an idea of what to take and what to do.
Every situation has a solution!

*The information I just posted should not be intended as medical advice and it is based on personal experiences.