Squishy should, ideally, be fed anywhere from 2-4 pellets depending on size up to 2 times a day. Also, account one day for fasting. If you would like, you could feed a very small amount of frozen brine shrimp or frozen blood worms as a treat for your fish. Your fish should not be fed more than it can eat in under one minute as far as the frozen foods go. If your fish gets a larger belly after eating, you may be feeding him too much, so try to cut back a little.
I'm only showing you the link for pictures sake, but the info isn't too bad, really.
http://www.bettatalk.com/food.htm
Not all pet store employees know what they are talking about, particularly the ones at larger chains. You are lucky if you find one who does, unfortunately. They don't want you to think that fish are difficult to take care of, so they tell you to feed you fish less. This, in turn, will cause your fish to poop less. Which, following, will be less to pick up after in the tank.
This is not taking care of a fish!!!!
I hope this helps some. I'm sorry if the pet store employees confused you. They do this a lot....just take all info you get with a grain of salt and compare. If it seems logical, and your gut is telling you it is right, then it probably is.