It doesn't sound like you're just not attracted to her, it sounds like you are actually a little repulsed by her.
I'm of the belief that people can do whatever they want and different things work - maybe you need initial attraction to someone physically or maybe you grow more and more attracted to someone based on their personality (we've all experienced both, I'm sure). There is no hard and fast rule to how relationships must start, and what they must have by a specific time to be successful. Every relationship is unique. And while they do need love and trust, (as well as attraction) those things aren't always immediate, nor are they all of nothing. Both build over time.
And while you do have a point about looks fading with time, I worry when you say you will "force" yourself to have sex with her. That's no good, dude. You're setting yourself up for resenting her and feeling gross/used. Even with my bf who I love and am attracted to, if I have sex when I don't actually want to - I feel terrible after and I am inwardly upset with him for a while (thus, I don't do that anymore).
I worry about you talking about deadlines, too. You're only 30. And you can date younger women. It's actually an annoying fact, but women have a harder time finding dates after age 26, and for men, not so much (source: http://blog.okcupid.com/index.php/the-case-for-an-older-woman)
At 30, your life is not ending. You are not expiring. You still have time to find the right person and have kids together. It sounds like your gf could be this person, except you are not attracted to her.
I'm actually kind of worried about her. You mentioned anorexia, and she said something about her health.
There are one of two things happening here: either she can't help it, she's just one of those people who is very skinny no matter how much she eats or what she eats (they do exist, as do heavier people who can't seem to lose weight - I know plenty of people on both sides of this) or she may have an ED. This is a huge thing for me to jump to, so I'm not going to assume anything - your comment just jumped out at me and it's a red flag - I'm concerned. If there are genuine warning signs of an ED, that is a whole other issue to address.