Can I pregnant on Lo Loestrin Fe?

I was previously on this form of birth control, because of period problems(got it once every 3 months) and never got pregnant. Now I've lost about 40lbs and I get my period every month WITHOUT birth control. I have started my same birth control again which is Lo Loestrin Fe, only this time it's for protection. Should I up my dosage for birth control, or is it okay for me to stick with this?