You do have my sympathy, and I'm not gonna throw any shade on you. 
My first born was a daughter, and two of my female cousins had two daughters each, but the 4th female cousin I've got had all boys, She is the oldest (5 years between us all.) She has been desperate for a girl ever since I can remember. She had/has five boys ... She had one at 21, one at 23, one at 26, and another one at 33. Then the last at 40.
She cried her eyes out when the fourth one was a boy. Even more upsetting for her, because myself and my two other female cousins had all had a girl within the past year and a half before. At the age of 39 - her last chance saloon in her words - she had a fifth pregnancy, and the baby was born 3 days after her 40th birthday... She prayed and hoped that it was a girl. It was another boy. She sobbed for days, and wouldn't even hold him... She spent most of her 20s and 30s. wishing and praying that she could have a girl. She said 'it's so unfair!' As there are three female cousins of hers who all have girls and she doesn't.
My brother and the other male cousin had two boys each. My boy mum cousin had to have therapy for a few years, and even now - 20 years after her last one, she still doesn't know why she was so desperate for a girl. (Even now she has a tinge of sadness now and again at never having a daughter, but it is fleeting and rare now...) I always wanted a girl. I can't explain why ... I just really, really wanted one .. Would I have been disappointed if I'd had just boys? Probably. DH felt the same, he really wanted a daughter too, although like me, he didn't mind if he had a son also...
I don't know why so many people - women especially - are so desperate for a girl, because as many people have said, some women don't have the relationship with the daughter that they think they will have. I'm fortunate to have had a good relationship with mine. However, I didn't have the best relationship with my mother, and she didn't have a good relationship with hers. My mother and her mother before her favoured the boys in the family. The girls/daughters were always second best, and always had faults picked with them, whilst the boys could do no wrong.
What my cousin with the five boys has now is two (so far) lovely daughter in laws who she gets on with quite well, and 4 grandchildren. (2 boys and 2 girls.) She absolutely worships them, and they love her ... She sees them weekly. Her chance to spend time with little girls came. It just took a while ... I'm sure yours will come soon. 
Don't beat yourself up. You feel how you feel. ... You clearly love your sons. You just would have liked a daughter in addition, to them, not instead of them.. Don't let the haters get you down. People don't understand the intense longing and desperation for a daughter - which seems to be (as I say) quite common in women in the Western world moreso.
Look after yourself, and look after your little boys, and I know you'll have some little girls in your life in the not too distant future. especially your niece that's coming along soon. Don't be down and don't be blue. You'll be the best and coolest aunt ever. And your boys will love their little girl cousin! 😘
My boy mum cousin's sons know she always wanted a girl, and although she has loved them and cared for them all, they do all feel a little bit like 'would she have been happier if I had been a girl?' Especially the youngest one, who knows she had therapy when he turned out to be another boy! She was very vocal about it a few years ago, and I think it would have been better left unsaid. So if you do anything @DaisyEM try to not let your boys know how you feel.