Could I be pregnant?

I'm 23 years old. I have been ttc for 10 months now. Today is day 43 of my cycle and still haven't had a period. I took 2 pregnancy tests this week including 1 today in the mornin. Both neg. The past 2 months my cycle lenths were 34 & 37 days long. My husband and I baby danced from day 15-22 of my cycle this month. The only preg symptoms I could say I have had were: mild cramps and a bad headache for 1 day about 2 weeks ago...and this week I noticed my breasts felt firmer and heavier but not sore and no other symptoms. I don't want to stress over this becuz it could all be in my head. What advice can you give me? I would really appreciate it.