Stressed - health visitor encounter today

HI,

Saw the health visitor today and T has only put on 3 oz in two weeks. He is entirely breast fed at present. Has a history of being a little underweight, but above the 9th percentile, generally following his own little line (apart from when we all had the norovirus).Health Visitor is putting me under pressure to give baby rice. T is not swallowing food yet, just playing. He is not six months till 15th Feb, but I am still feeding on demand mainly every 3-4 hours day and night. How do I get some calories into him and do I need to? Can/should I give him baby rice just on his tray?
How can I convince the HV I am not a loon? How can I get him sleeping 6 hours or so just to give me a break? He did sleep 6-7 hours before he had the norovirus the week before Christmas.

Please help.

I didn't find the right solution from the Internet.

Thanks!