Hello there. Nope, no lectures from me...I've bought animals on impulse as well (as I'm sure many people have). The important factor is that you're trying to do right by the animal you've bought. In my personal opinion, I don't think you'll have any problems handling an adult boa. I'm 5'6" and 4 of my adult boas are in the 7' range - with the exception of one incident (totally my error), I've rarely had any problems. My best friend is 5'2" and quite petite...and she regularly handles her 8' female boa and her 7' male boa with no problems.
Fed reasonably, your baby boa will take several years to reach her adult size. In essence, you will grow together because as she grows you will learn her behaviours and moods and adjust accordingly. As to feeding schedules, I feed my babies 1-2 appropriately sized prey animal every 7-10 days (usually hopper or small mice), juveniles & sub-adults 1-2 appropriately sized prey items every 2 weeks (usually large mice for juveniles and small rats for the sub-adults), and adults an appropriately sized prey item every 3-4 weeks. By appropriately sized, I mean a prey animal that will leave a slight lump once swallowed - roughly 1 1/2 times the snake's widest diameter. Sometimes I will occasionally feed two smaller prey items instead, but usually just a single prey animal. There are others who recommend a heavier feeding schedule, but I personally prefer to grow my boas at a slower rate and keep them leaner. Obesity isn't healthy in any animal and because many boas and pythons are quite sedentary animals, I don't believe in feeding them quite so often. If nothing else, you can follow a defecation schedule where you feed your boa after it defecates its last meal.
It is also important to the health of your boa that her environment is correct - temperature, humidity, fresh clean water and hides are all important factors. Learn as much as you can and you'll find yourself with a wonderful pet for many, many years.
Raven