A saxophone embouchure is different from a clarinet embouchure.  If you are still tucking your lip in over your lower teeth you need to change that.  Take plenty of mouthpiece into your mouth beyond the break of the tip opening, rest your top teeth lightly on the mouthpiece, and roll your lower lip out slightly.  Keep the corners of your mouth at the level of the reed.  Play long tones, working your way down.  If after several days of practice you're still having difficulty, you might try a softer reed.  It would also help to have at least one lesson with an instructor who can see what you are doing and correct any bad habits that they see developing.  If there are none in your area, skype lessons are available.