Thanks for responding!
I actually switched from alesse because I felt moody and hungry all the time. After I got my period early I was concerned that the hormones from the alesse weren't stopping me from ovulating but that is not the reason I switched to yasmin.
I'm relieved to hear that as long as i've been careful about taking the pill everyday for a month, switching the brand shouldn't change anything. I couldn't find any information about that on the internet so your input is much appreciated!