Maybe I'm to old for baby # 3 ??

My oldest daughter is 15 years old 
​My youngest daughter is 4 years old 
​And we are hoping & trying for a BOY .....  It is so tough sometimes because we have opposit schedules he works 10pm - 6am I work 7a7p ?
​I'm 37 years old my husband is 34 
 am I too old ??  Since we had our little girl who is 4 we never used birth control ever ..  We were not even trying at all . It just makes me think I'm to old ..  Maybe I'm over thinking