Brief Answer:
Discuss my following suggestion with your treating psychiatrist

Detailed Answer:
Dear,
welcome to HCM
I can see that you are suffering from multiple co morbid conditions and I am suspecting a strong possibility of associated anxiety-depressive condition.
Insomnia, fatigueability, bodily symtpoms are strongly suggestive of depression and anxiety.
If there exists are other aymptoms of low mood, persistent worry, loss of interest in routine activities, hopeless XXXXXXX helplessness, etc then it confirms a clinical diagnosis of depression.
Presence of HTN, DM2, etc again increases the risk of depression and anxiety disorders.

My point is to help you understand that your problem may not be just of sleep, but a more bigger condition of depressive-anxiety disorder, which not only explains your insomnia but also other associated symptoms.

The decision of not giving you sleep medications could be justified by the fact that 1) they are less recommended in higher age, 2) you have mentioned about TIA is history, and 3) multiple medical conditions. Considering these, sleep medications should better be avoided.

Therofere, our focus remains to find a better alternative over duloxetine, that can help to correct problems of depressive state(if present), insomnia and fibromyalgia. At the same time it being less interactive with concurrent medications and safe.
My suggestions to you
1) Kindly discuss with your treating psychiatrist about replacing duloxetine with Mirtazepine, or lowering the doses of duloxetine and augmenting it with Mirtazepine 15 mg during bedtime.
my explanation for this suggestion-
Mirtazepine has a sedative property, therefore it will correct insomnia, good alternative to SSRI for depressive-anxiety conditions, safe in cardiac patients( ref- Maudsley).
Therefore, tab Miratzepine 15 mg at night can be added, while reducing Dose of duloxetine so that the serotonin toxicity is less.
2) lifestyle modifications promoting healthy sleep hygeine should be practiced.
you can send me your daily routine details and then I shall suggested you some changes.

DO NOT TAKE SUMATRIPTAN with duloxetine or Mirtazepine as it may lead to side effects.

NOTE: ANY CHANGES IN MEDICATIONS SHOULD BE MADE STRICTLY ON THE ADVICE OF TREATING DOCTOR, AS SUDDEN DISCONTIUNATION CAN AGGRAVATE UNDERLYING CONDITIONS.

Kindly discuss my suggestions with your treating consultant.

Do not worry, the problem has Cure, however couple of consultation and changes in medications could be required.
You can revert back anytime for more suggestions.
Thank you.

Regards

---