I absolutely have to have everything in my house arranged in order of size - what can I do to stop?

OCD. Tx is available, if your symptoms are interfering with your daily functioning or causing distress. Talk to a mental health professional. Cognitive Behavior therapy with or without Medications for obsessive thoughts, might help.
CBT plus meds. Response prevention techniques plus certain medications are the treatment of choice for OCD is that is the diagnosis.
CBT plus meds. Cognitive-behavioral therapy will help one take an alternative way of looking at the world in addition to ssri antidepresants.