You can feed your baby breast milk, but the fact is that only breast feeding will not be nutritionally sufficient for the baby. There is no documentation that breast milk become thick or such after 1year. But baby should be slowly weaned off from breastfeeding after 6months-1year age for baby's better growth & mother's proper menstrual cycle.
Next Steps
Try to make your baby quit breastfeeding slowly.
Health Tips
Feed baby with nutritious diet and supplements.