Lost hope conceiving again.

I'm really hurting right now. My husband and I have been trying for a year after our youngest child turned two because we both agree to wait after our son turned two years old now that he is three years old. And we have been following my app on Glow for awhile now and another app before this one no luck whatsoever even having sex on my fertile days. Both of us been to the doctors and was giving a clean bill of health beside me having diabetes type 2 I've been controlling my diabetes, watching what I eat and stop eating after a certain hour before bedtime. I don't drink nor do drugs neither does my husband both of us are on multivitamins to increase our chances in getting blessed with another bundle of joy. But I'm losing hope in having another child I shouldn't because I really do want another girl I have six boys two are grown, one's a preteen and my two young boys are two years apart I have one teenage girl who will be 18 in three months. She'll be leaving to attend college after she graduate in for which we're very proud of her but I'm gonna miss her and I wanted to have another girl so she won't be the only girl but my family told my not to have another girl just to replace my oldest daughter I don't see it that way for my daughter always wanted a little sister but she ended up with three younger brothers who looks up to her. I don't know but I'm so confused now that I'm in tears.