Is my tank overstocked?

I've set up a 55 gallon tank and am wondering if I have too many fish in it (especially considering the runaround i've gotten in regards to the full grown size of a Colombian Shark ) I have a Colombian Shark, a Blushing Angelfish, a Rainbow Shark, a Sterba's Cory, a Pleco, two female Swordtails (their mate recently died) and a Betta splenden. The fish get along great (there was a little bit of a war between my Angelfish and Betta at first because my Betta was a replacement of the first one who got eaten by a crayfish we introduced to the tank, but they don't pay attention to eachother anymore) But I have noticed that my Angelfish has stopped growing and he is supposed to grow to be a much larger fish (although I could just be being impatient). And I really have no idea how big my sharks will get, as the people at the pet store said he would only be 8-10 inches when full grown. Stupid me for believing them. Anyways, any input would be great! Thanks so much

okay good to know so do you think it would be safe to add a couple extras??? ((like a maybe a couple more corys and angels???)) definitely no bettas tho and i think the sharks seem pretty content with eachothers company. My colombian shark used to hang out with the cory all day, but lately since he's grown so much bigger he just chases the cory away from his hiding spot but at least he's become friends with the rainbow shark since then, just too bad for the cory

currently, the colombian shark is about 7 inches and the rainbow shark is 6