First off, welcome to the forum. It's good to see more females involved in the sport. First and foremost, you have to hit what you're shooting at. If you have to crank your bow below 40lbs to shoot accurately, by all means do so. IMOCD gave good minimum KE parameters, and for you that will be accomplished by using a heavier arrow. Play with arrow weights and you'll find a"sweet spot" where yourKE is just about maxed out but trajectory does not suffer too badly. A two bladed broadhead like the Muzzy Phantom or the before mentioned Simmons Sharks are very good heads.
BTW-I'm 33yrs. old. I'm 5'4", and weight is classified information. I've been bowhunting for 7 yrs. I'm convinced that I'll neverrequire a bow with a draw weight beyond 55lbs. My current bow is set at 51lbs. I need to practice year round to comfortably and accurately shoot a 50lb+ bow.