It sounds like you and your boyfriend are being really mindful about safer sex, which is great. We are strong proponents of combining two methods of contraceptives, called the The Buddy System
. Whilst no method of birth control can be 100% effective, combining two methods brings you as close to this as you can get.
As you'll be able to see in the linked The Buddy System
article, the maths on the effectiveness of using a condom in combination with a Combination Oral Contraceptive like Yasmin is 99.99% effective with perfect use - 98.7% effective with typical use.
In the article you'll see that three or more simultaneous methods are not calculated or recommended as the increase in effectiveness will be minimal if anything. The article shows the maths on lots of different scenarions and links through to our comprehensive guide to birth control, Birth Control Bingo
, which could be useful if you're curious about trying a different pairing at any time.
If you have any questions about the above, please don't hesitate to ask.