Hurray! Welcome to theVampire Club! 151 is a nice +6 for a beginning diabetic. Here's a general guide:
We consider a cat regulated if they are in the mid 200s at preshot and 100 or under at nadir (+6). 40 and under at nadir is getting too low and requires intervention with food and possibly honey (if the levels continue to fall - it's what we consider a hypo). We like to see a new diabetic not get insulin on a preshot 200 and under. It is okay once you have been testing awhile and know your kitty's patterns, but not at first. If you get a preshot 200 or under, wait 20 minutes without feeding (food artifically brings up levels) and retest to be sure it is risng and over 200. If so, shoot a little less than the previous shot.
Did you sure reward both of you after the 10 tries? A low carb treat for her and something for yourself (chocolate is sometimes nice). The treat after is important so she will continue to allow you to poke her.