I feel your struggle.I was always too scared to ask a fat girl out, because as a shy and introvert person, the last thing I wanted to do was stand out from the crowd and being out of the norm.
That's also why I stayed single for a long time. When I finally met and got together with my first girlfriend, my family and friends were of course anxious to see her. I immediately got those comments from my mom that she was big, and that I could do "better". She kept on making comments from time to time and remained negative about her. I think also one of my friends made some comments.
Now, she had BPD and my family and friends were right that she was not good for me, but at some point it is difficult to differentiate between them being negative about her because of her appearance or because of her character. When I finally divorced her, their was a sigh a relief from my mom (and me!), but soon after she commented that she was glad that we divorced and that she knows that I don't mind if a woman is a bit bigger, but that she hoped that my next girlfriend would not be so big (she was about 5"5' and 300 lbs / 1.68m & 135 kg at her peak). That's when I told my mom very firmly that she could be glad for the divorce because she was an evil person, and that she can comment (within reason) if she really thinks someone is not right for me, but that what my girlfriend looks like is my choice, that I prefer that they are a bit bigger and that I don't want her to comment on that ever.
My next gf was less big, but still BBW, but also had some mental issues (mainly depression). I could tell that my mom was not always happy with my choice, but she never made any comment. My current wife was quite big as well, but well educated, respectful job and mentally stable and my family really embraced her without comments.
With regards to my friends: I have one really alpha male friend who is very vocal about his taste of women, and I think he may have made some comments in the beginning about my first gf, and she could feel how he didn't like her, but then again I can't really blame them for not liking her, I was just too binded myself. But shortly after me, another friend in our group showed up with a big gf and by now this alpha male has just accepted that his to closest friends just like a totally different type of women than he does.
Long story short: tell your family and friends that they need to back off. They should judge her by who she is, not what she looks like. Tell them you like what you like, and that is some softness to cuddle. If they love you, they should be happy that you are happy, even if it is not their ideal.