An iron level of 25 and a
thyroid reading of 8.4 both point toward anaemia and an underactive thyroid, both very common eleven months after a c section and while breastfeeding, and both can explain the weakness, dizziness and weight gain you're describing. The exhaustion and feeling overwhelmed while caring for your baby mostly alone matter just as much as the numbers.
Next Steps
Please see your gynaecologist or a physician soon to get your iron and
thyroid treatment adjusted properly, since both usually need monitoring and dose changes over time. Also mention how overwhelmed you're feeling, exhaustion this severe is worth screening for postpartum depression, and even a little practical help at home will make a real difference.
Health Tips
Seek care urgently if you feel faint on standing, your heart races, or you have thoughts of harming yourself.