@AfterGlow87. The colour of your milk sounds right on track for this transition stage. Also, increasing amounts of 5/10 ml a day sounds perfect too. From what you've described, I'd say you've just experienced a very slight delay (understandable after a c section and on being separated from your baby), but you are only a day or two 'behind'. And because your baby is premature, with a tiny stomach, this tiny delay shouldn't matter at all. Obviously, the staff in the hospital are best placed to know if the amounts of milk you are expressing are currently enough, but my opinion is that those kind of volumes, produced every 2 or 3 hours, will be more than sufficient for a premature baby.
Once your baby is a little older and stronger, their sucking at the breast will help to build up your supply even more, but meanwhile your pumping schedule sounds perfect and the amounts of milk are increasing at an expected rate, if a day or two behind.
As for expressing, make sure you are warm, comfortable and relaxed and thinking about, or looking at, a picture of your baby. Also try putting a sock over the bottle into which you are pumping.... It really helps to decrease anxiety when you can't constantly see the amounts you are producing!
But mostly, I'll just repeat my point that at this stage, even with a 'normal' delivery and full term baby, the amounts of milk per feed would only still be relatively small... 40-60 ml, as described previously. Well done! You are doing fabulously and you will see rewards for your efforts every day, as the volume of milk creeps up. It is the best thing you can do for a premature baby, so... A big well done! So glad to hear your baby is doing well x