Beagle Mom
Additionally, she uses a doggy door, so I have spent the last seven days running out the door every time I heard her go outside,

LOCK it for the duration!!  Seriously -- you do *not* want this girl outside unattended literally even for a minute!  She'll wind up tied with a  neighbor dog (they can scent a female in heat up to 5 miles away -- and they don't care if they are bigger than she is or not!!).  Go out with her and if it were me I'd have her on a long leash simply because during part of her heat cycle she is going to be every bit as eager to tie with a male as he is to her!!  You may not be able to get her away from a male in time (because she's likely going to ignore you).  You'll have far more control with a leash on her!