Refill 10mL bottle from ampules

I've been using 10mL bottles and injecting .4mL at a time. On my last order my supplier substituted my 10mL bottle for 10 1mL ampules. I'm in a bit of a dilemma as I will have .6mL left over each injection and trying to minimize waste. Some have said to just prefill the next syringe but I've heard the rubber in it can degrade and contaminate the solution. My other thought is to just buy sterile 10mL bottles and put the testosterone in those. Is that safe to do? I saw someone post that the testosterone in ampules does not have to benzyl alcohol mixed with it which is supposed to keep it sterile upon opening making it for one time use only and not multi use. Looking at the ingredients, these amps contain .9% benzyl alcohol while my 10mL had 2% benzyl alcohol. Will it be safe to fill a 10mL sterile bottle with the testosterone from the amps? Or other ideas to minimize waste?