Why is my period always late like this?

im 17 and ive had my period since i was about your age and it is literally just now starting to settle into a normal pattern. nothing is wrong with you, it's really normal for girls who just got their periods to not have it on an exact routine and to have varying heaviness. heck once it took 40 days for me to get and that totally freaked me out since it was 21 days the time before. periods are wierd like that unfortunately. the best thing to do is just look for the signs that its coming (these vary a little for each girl and the longer you have it the better you'll learn yours) instead of worrying so much about the days. Some of the signs could be: back pain, tenderness of breasts, that mucus like discharge you're talking about, wierd cravings or having a huge increase/decrease in appietite (that one depends on the person), acne, irribitness or cramping like pains on one side of your body in your lower half. you could buy some pads to use on days when you feel you might be close,even if you would rather wear tampons during your actual period. that's safer than using a tampon when you dont actually have it since its not really enough moisture to slide it in there comfotably. don'y forget the timing of your period can also be affected by things like stress. i hope this helps and try not to worry so much, you'll be fine, i promise :)