Hi. Technically my bub is not IUGR. However she is in the 3rd percentile. She's currently 4 and half months, still in newborn nappies and is borderline wearing 000. She still wears her 0000!!!
She was 2.9kgs at birth but has a condition which affects her growth. I saw you mentioned feeding problems of which I'm well versed at!! I had to stop breastfeeding her as she was burning too many calories. I exclusively pumped for 3 ish months. I had LOTS of trouble with feeding and bottles and falling asleep. The only bottle that I've had success with are the slimline bottles with pigeon peristaltic teats. The speech therapist tells me this type are closest to breastfeeding. Avent bottles and closer to nature have short teats which are harder work for bubs.
I thought it would never get easier... Some days it was like she would feed for a minute then sleep for 30 minutes then cry because she was hungry. I called it grazing all day and night. I did initially do bf then top ups too. She didn't gain enough weight and we had a stint with ng tube. She's had heart surgery too. After that the feeding was hard...
After some hard days and many tears I'm managing to get her to feed more routinely and effectively. At 4 months now its s huge improvement. She even gains usually over 200g per week and feeds every 3 hours. I do make formula extra strength with advice from the hospital dietician.
So even though not the same exact issues from my experience so far it has gotten easier. But I had some shocker days and still do, but the bad days are less now.
(With regard to nappies... Snugglers I think they're called do a premmie size. We used them for a week or so).