I'm the same with my boyfriend, although he admits to having a high sex drive like myself but mine just seems far to extreem, im not a greedy fuck either. I just like the connection and rush i get from it.
I like to wake him up with sex and it seems to get too much for him some of the time... sometimes it's like i wish there was a "hang on don't cum yet" switch, but i havent found one if there is.
I would say to talk to her about it and tell her you're not being selfish, more the oposite. You want her to feel as good as you do when you're having sex with her.
Also, have you ever tried teasing her, or sending her filthy messages suggesting sex or blatently telling her you want her, this might help, wind her up with it, turn her on, make her want it.
If all else fails, try experimenting with yourself more, or buy a toy that she can use on you, vice versa, instead of it always being intercourse try more outercourse, even if it doesnt result in sex.
The filthy texts usually work for me, or have you tried dressing up for her for when she comes home from work or something?
Do something she wouldnt expect you to do, and see how it goes. x