Hi there! Well, fantastic news you use birth control! that's great. Sadly, birth control can fail which is always a worry -- makes abstinence the only known way to never get pregnant.
I wouldn't jump to pregnancy though for why your period is late. If you had conceived around the time you speak of, you'd have probably not be having symptoms this early. The reason why we have symptoms is because the hormones of the pregnancy accumulate and causes them. It takes time for this to happen. Nausea, for example, doesn't start until week 6 to 7 of pregnancy for that reason.
Your period is currently how many days late? If you have missed it, you can take a pregnancy test to find out. I will tell you that this is a common year for women to have a late period due to all that goes on-- change in schedule, illness, stress, gaining weight, etc. which is all common around the holidays.
good luck
It's very likely you could be. Test in a week or so and it will tell you.