If you used a preemie formula for your LO, at what point did you switch? And what did you switch to?

DD3 is 8 months old - when she was new, I did a combination of formula and formula mixed with breastmilk to up her calorie intake since she was IUGR and not gaining weight well. At this point I'm facing less pressure on weight gain (though she's still very small), and no longer use formula as a supplement (I breastfeed, and if she gets a pumped bottle, I don't add formula). I'm just finding that as I go back to the gym and don't have much frozen breastmilk, I need to be able to leave her a bottle in the childcare room, and am about to run out of Neosure. The cannister says "for the first year", so I'm thinking I'll just stick with what we know, but I wanted to see if anyone else had experience with changing formulas, particularly if it's for occasional use only, and knows if there
might be a reason I should consider switching.