H007, how worrying for you....yes, you can return to fully breastfeeding, and this setback does not have to be permanent.
No one here can tell you what to do or advise you to go against what the medics/SCBU are asking you to do.
But.
You can certainly ask for a good discussion, because topping up from birth, and giving formula for jaundice, may not be the advice of a maternity unit well-versed in breastfeeding support (no matter what they are actually saying to you - support means more than words, it means knowledge and ability to help you sustain bf even in the face of problems).
The doctor may be being 'over cautious' because he simply does not know much about sustaining bf in these circumstances, and he is relying on the 'safety' of what he knows more about.
You could deffo ask to see the infant feeding adviser, you could also ask the doc if he is aware of NICE guidance on the topic of jaundice in the newborn and the importance of breastfeeding continuing, even when the baby is being treated www.nice.org.uk/CG98. Size of baby is normally no good reason for supplementing with formula, and jaundice is usually 'treatable' with ad lib breastfeeding/expressed breastmilk or colostrum. In serious cases, however, formula may be justified. You need to be sure in your case that it is.
Hope things go well for you and your baby.