I was recently diagnosed with add and have started taking vyvanse for it. I started on 20 mugs and had the common side effects that subsided in the first 2 to 3 days such as headaches, feeling disoriented, cotton mouth, and nausea. I continued on with the 20 mugs for 2 weeks until I felt they weren't helping as much as they should be so my doctor bumped me up to 30mg. I was supposed to be on it for 1 week and then if I needed he would bump up my dose, I did feel depressed for most of the week so he kept me on it to make sure it wasn't a side effect. Well on the 30 mg I reported having chest pain but my doctor said that was not the medication. I was eventually bumped up to 40 mg (what I'm on currently). I started to get major dizzy spells (worst then normal), and I released I hadn't had my period for 2 cycles.
I have thyroid disease in my family history but no other medical conditions I know of. I was tested for thyroid and it came back clean so my family wiped that from my possible problems.
Is this the medication making my skip my period? Is it not for me or is it something else?

Stress is a big one and probably a major factor in this case. I don't know the specifics of the drug you're on, but if it is meddling with your body chemistry then there is a good chance that it's having an effect on your cycle. Did you bring this up with your doctor?

Are you sexually active? Is pregnancy a possibility?

This is best discussed with the doctor that's handling your case. He knows your medical history, they medication, and everything else. Any answer you get online, will not be based on you, just possibilities, and not a good idea at all. Talk to your doctor about this. Good luck.