I don't think, if the baby has been transfuse at an age of 4 months, baby is intermidia thal. But do as Andy said, stay in touch with ur hemo.
For fixing needle,
Give some Tea, coffee before 20-30 minutes of pricking needle. Remains hydrate.
Find a nurse or doctor who works in pediatric dept and knows to fix needle without fail. Morover, Do a soft ball exercise to make veins easily available