i don't have any experience with the Bilt brand of helmets, but i see that they are at least DOT certified which is a plus. HJC makes a good helmet and they are on the more affordable side (though still more expensive than Bilt's.)
a lot of helmet comfort/sizing seems to do with head shape. i must have a good shaped head because i have never had a problem with sizing (always a small) so i don't really have any fear of ordering a helmet online. if ordering, make sure that you use a good measuring tape or something and either look in the mirror or have someone else look to see what the measurement is. you want it to be snug but not too tight so that it will give you a headache.
i'd just stick with what you already have. as long as it will protect your face in the event of an off then you're good.
also, there's nothing wrong with having more than one helmet!
you should also look into some other protective gear like an armored jacket and gloves. i'm not going to tell you to wear all the gear all the time (ATGATT) but there's nothing fun about road rash.
do you have a motorcycle endorsement on your license? if not, i recommend signing up for the MSF class asap. i cannot express how much i enjoyed the class and how much it helped me learn to ride well, spot dangerous situations, etc.