Hi Tellytubby

I'll give you my honest opinion, I don't think it was inappropriate or disrespectful. Perhaps some mums may have moved to the back, but some may have done exacty like you. There is no right or wrong way! What you did was absolutely fine, don't worry. I guarentee the 'sea of people' weren't focussed on your boobies.
I think the only thing that would have made it inappropriate was if your grandma next to you felt uncomfortable with you bf'ing (just out of respect for her since it was her day sort of thing). Though I'm sure she didn't, it was probably a comfort to her watching you display show much love to your little one during such an emotional moment.

I bfed at my grandads funeral as my son was kicking up a big fuss.