My experience with Loestrin 24 was that I had spotting/breakthrough bleeding for most of the first 3 months. It was hard to tell what was spotting and what was my period. I felt like I spent 3 months straight on my period!! I ended up having to go off of bc pills completely after just 5 months as the headaches were unbearable and my blood sugar went nuts (never ever had that issue before) plus my cholesterol jumped up over 40 pts. I am 43 though so although I fit the profile to still be able to take the pill after 35, I apparently cannot anymore. I had the same lightheaded feeling you describe. Since everyone is different, I would probably try to stay on it for a couple of more packs to see if it calms down....unless you start feeling really, really bad. Maybe your body needs some more time to adjust. Take care.