One tip is to count your low hand like a 5 digit number and don't focus on your low cards on their own (which in your case look "great" but don't make the best low) - this will force you to count the cards in your low hand from high to low (and not the other way round which is incorrect).
So think what "number" you have.. 84,321
What is best villain can have with his up cards? 76,4xx
So he can have a hand that beats you (if he can make a low with cards under the 7).
in this case he made 76,542 as he had a 5 and a 2 hidden.