Only real way to know for sure would either have it independently tested by a lab or a more easy way would be to do a melting point test on it. If it's really Test E it will have a really low melting point somewhere in the 80 degrees range. It will melt on it's own just in a really hot room. On the other hand if it's Cypionate it will have a much higher melting point closer to 200 degrees. It does sound like you may have received Cypionate or one of the shorter esters of testosterone. Test E should hold fine at 300 mg/ml with even a minimal amount of BB. Somethings not adding up. I always work with Test E if I'm using a long ester Test. So easy to work with. Cypionate on the other hand is a bitch no matter what compound it's attached to. Wish I could be more help but I think the only way to test it out a little bit would be to do a melting point test on it and see.