Don't worry.
My advice to anyone is to write as many characters and POV characters as you feel you need to tell the story. When you come to revise -- whether that's at the end of the first draft or the end of the first chapter (or first page) -- you have to justify everything you've written, to see if it does enough to warrant its place in the novel. That includes the number of characters and POVs you've chosen. In revision the characters and/or POVs can be consolidated or removed, or new ones added as needed.
The problem with Thou Must Only Have One POV Character, is that if she's not at an important event which the reader needs to know about, then you're reliant on the detail being given to her second or third hand. It's perfectly possible to do that well, but frankly I think a new writer who is still finding his writing feet is better off going the route of bringing in another POV, someone who is there at the event, since the writing of that will be more direct and interesting, whereas in inexperienced hands the second/third hand relation can all too easily become badly dumped backstory.
To my mind the problem TheAlchemist has isn't the number of characters or even POV characters, it's the number of main characters and the wish to show each of them in his/her own quest. Writing an ensemble novel, where every character has to be given equal weight and time is difficult, and especially so if there's a need to show all of them in a short space of time. That is certainly something I wouldn't recommend to someone just starting out.