Hi there, you are through to Dr. Jake. Im a UK based vet. im sorry to hear of your concern with your tortoise. the signs you describe could be due to multiple reasons.
if he hasnt put on any weight then this could be due to:
lack of eating- this can be due to malformation with the mouth which makes it difficult for them to eat
poor nutrition- its important that adequate fresh veg is provided daily and supplemented with vitamin and mineral powders regularly alongside adequate ultraviolet lighting with a high % such as 10-12% for tortoises
competition for eating - if your tortoises are together then they will need to be split up when mature as tortoises are territorial and will fight if in close proximity to others.
gastrointestinal parasites can lead to lack of weight gain which would require a faecal exam analysis and treatment by a local vet who has experience in reptiles.
the eyes being closed could be due to chronic malnutrition as above, it can also be due to inadequate temperatures resulting in semi hibernation - temperatures at the basking spot should be atleast 30 degrees with a background temperature of 27 degrees- this should be monitored with a digital thermometer with a probe
the closed eyes can also be a sign of an eye infection - in tortoises this can occur due to multiple reasons but lack of vitamin A can predispose this so make sure you have a diet and supplement which contains vitamin A
as this tortoise is young, small and hasnt gained weight i would recommend making an appointment with a local vet who is experienced in reptiles who will be able to conduct a full examination, if an eye infection is suspected then treatment for this can be provided, if other underlying conditions are evident then further tests such as blood tests and x rays may be required . i would recommend taking a stool sample for this to be analysed under the microscope to rule out parasites
i hope all this information helps