Before getting into a needed discussion of your status, please tell us why you think you might be a little hyper, even with those relatively low Free T4 and Free T3 results.
Your Free T4 is below range, and your Free T3 is too low in the range, consistent with being hypothyroid. Although a higher heart rate and headaches are frequently thought to be hyper symptoms, as you mentioned, they also can be due to being hypo. From a very long list of symptoms that can be related to hypothyroidism, note these sections.
High blood pressure
Low blood pressure
Slow/weak pulse (under 60 bpm)
Fast pulse (over 90 bpm at rest)
Arrhythmia (irregular heartbeat)
High LDL (“bad”) cholesterol
Mitral Valve Prolapse
Coronary Artery Disease
Elevated C-Reactive Protein
Congestive Heart Failure
Wanting to be solitary
Feelings of resentment
Lack of confidence
So the big question is why your Free T4 and Free T3 levels are so low with the relatively high doses of Armour and T3. There are three possibilities that come to mind. One is poor absorption of the meds. The second would be excessive Reverse T3. The other is the possibility of high levels of Thyroxine Binding Globulin that can result in low amounts of FT4 and FT3 in spite of having high levels of Total T4 and Total T3. The excess TBG can be a result of a low ratio of progesterone to estradiol. So I think it would be a good idea to test again for Free T4, Free T3, Reverse T3, Total T4 and Total T3, along with progesterone and estradiol. From those tests the cause should be apparent.
Regarding your question about low Free T4, it is always lower relative to Free T3 because the ratio of T4 to T3 in Armour and other desiccated type thyroid meds is only 4. Also, just for info, be aware that when taking desiccated thyroid meds like Armour Thyroid it is best to split the dose and take half in the morning and half in the early afternoon, to even out the effect over the day. Also it is best to defer the morning dose until after the blood draw for thyroid tests. This avoids false high readings for Free T3.
Can you get those tests done?