Maybe you should the tip of the reed more "outer" than from the tip of the mouthpiece, coz the embrochure each person creates is DIFFRENT, so it dosen't have a right or wrong embrochure, bu it still av a BASIC LOOK. So,
First, maybe it's your reed position problem;
2nd, maybe it's you airstream problem.;
3rd, if you haven't played the clarinet before, or somebody teaches you the basics, play the mouthpiece without the instrument first, (comes with the barrel), untill you've take a hang of the sound and embrochure, then you connects the instrument. while playing the lower register notes, relax more than playing the higher register notes, and remember that the airstream between playing the higher and lower register notes are NOT THE SAME.
4th, ask a clarinet player to carrects your playing erorrs, coz you never know until someone tells you.