Symptoms??

Hi everyone!
​My husband and I are trying to conceive our second child. My daughter will be 10 months old this weekend and she is breastfed.  I have been getting a period for a couple months. This month we had sex 2 times during ovulation and I am due for my period the 22. Could I be feeling some symptoms already or is it too early?  The other night I had heartburn which the last time I had that I was pregnant with my daughter. I have been getting those lightheaded feelings, and tonight i gagged changing a very messy diaper....another first.  Could this all be in my head....or a possibility??  
​Thanks!!