Yaz Birth Control?

I will be on birth control for two months January 5th. I am currently taking Yasmin. My boyfriend and I are in a serious, monogamous relationship, we both know eachother's pasts, and have both been tested. Recently I have been experiencing l dryness, not a lot, but much more dryer than I used to be. Could this be a side affect of birth control? My boyfriend and I have ALWAYS used condoms, including the past two months I have been on birth control. But with me being not as wet they get very dry and are very uncomfortable. We are going to start using lubricant but I was wondering if spermicide would be a good option also, just as a backup method? And also how long until I would have to wait to have unprotected altogether after I have started birth control? Thanks!