Re: loestrin 1/20 light periods?
Really low dose pills can have that effect. Some women will stop getting them altogether (really small %). If it starts to become bothersome, you can consider switching to a pill with a higher estrogen. (necon 1/35/ortho novum, or estrostep have the same amount of the same progestin, with a higher dose of estrogen)
You shouldn't be worried about pregnancy unless you screwed up taking the pills this month.