Are the T3 and T4 free T3 and free T4 or total T3 and total T4. The numbers and ranges look like totals to me. If it doesn't specifically say "free" on your lab report, it's total.
TPOab is elevated, so you have an autoimmune thyroid disease, either Hashimoto's thyroiditis (hypo) or Graves' (hyper).
TSH is very low, which often indicates hyper, but TSH is a pituitary hormone and can be affected by any number of factors. You mention LBP, which is usually a symptom of hypo. Do you have any other hypo symptoms...low HR, weight gain, fatigue and/or drowsiness, constipation, hair loss, depression, etc.?
T4 7 (4.5-12)
T3 78 (71-180)
TPO 251 (0-34).
TSH: < 0.006 (0.450 - 4.500)
Please post your actual FT3, FT4 and TPOab results with reference ranges. Ranges vary lab to lab and have to come from your own lab report.