How soon is too soon?

So my husband and I just recently starting trying (like within the last week and a half) and for almost a week I have been completely exhausted!! I get headaches every day, feeling nauseous here and there, and am so tired. I will get 10-12 hours of sleep a night and then need a 3-4 hour nap during the day! I am a teacher on summer break so I am able to take a nap when I need it but I am not doing any activities out of the ordinary so I don't get why I'm so tired. Could I be pregnant? And would I be feeling symptoms that soon?

Update: I'm 4 weeks along!