I have seen this all over the place in san diego. All these good looking white guys dating bigger white women. And some treat their men bad. So why is it that white men will not date a bigger mixed or black female? even if they are just as pretty?

You may see white males dating large white females, however, you usually do not see white professional/successful men dating large women. Professional men go for image, whatever makes them look good and stand out. The ego of these men really rule.

Off subject but here in the Rocky Mountains to see a black man with a big white woman is a daily occurrence ! Now go figure 🙈just plain interesting.

By the way, you are beautiful. You need to put up more pics of you smiling!

Maybe things are different in Boston, but I haven't seen white men dating very heavy or very thin women. Most of the white wealthy and powerful men I know, tend to marry healthy looking women. I.e. women who you look at and think, she has a nice shape, but there is nothing remarkable about her weight at all. Most of these men do not want a woman that will create notable shock value. Which also explains why alot of them ultimately do not marry interracially, even if they date outside their race. 
I think the shock value of being in an interracial relationship is enough for many of these men to decide that if they do go this route, they want their partner to be "unremarkable" in other ways. 
For example, the number of wealthy white men who wouldnt be interested in me if I decided I wanted to wear my natural hair/locks would be significant. Not because I am not attractive or whatever, but most of them just aren't willing to have this extra piece of social curiousity added to their relationship. 
I would take it less personally and think of it more as a construction of alot of social factors. Remember, beauty is a social construct. As much as women feel the pressure, certain men feel the pressure to find a mate who fits into that.
Consider yourself lucky, because the man that you end up with will likely be progressive, interesting and have more balls than average. The right man will see your difference as an asset, not a liability. 
And although comparing women to cars is RIDICULOUS...and makes me want to pull out my hair (tracks and all), the comparison of the thought process is almost perfect. Do you want that middle aged guy driving around in a convertible trying to prove something to the world, or do you want someone who knows an effing car doesn't define him and drives whatever the hell he wants.
Not everyone is chasing convertibles, thank God.

Depends on what you mean by "full figured"

I have noticed that the thinner I become the more attention I get from caucasian men.  I think that they just like smaller women.  Not all but at least the ones that I have run into.  I think that every culture has it's own characteristics that they prize.  You can see that around the globe.  But more than anything, it's confidence.  If you're showing, in actions or words, that you somehow feel inferior .. they will pick up on it.
Do you.  Be the best person you can be.  Someone who will look at only a person's size is too shallow to deal with.

Your turn will come, just keep your health a top priority.

I hadn't noticed successful white men dating full figured women of any race. I think most men date women who they believe their friends, collegues and neighbors will view as a trophy. Overweight women, older women and any woman who is not white are usually not viewed as trophy women. A trophy woman is young, thin, with long hair. Sometimes this includes mixed race, Latina and Asian women. Men are very competetive with each other. Women are just part of how men keep score. If a man thinks a woman's ethnicity, size or personality will pull down his social status vis-a-vis other men, he won't date her. Forget about marrying her. There are some men who are very secure with themselves and will date a person based on her character, but mostly, men are visual and competetive. Some men have scored so high on their own, without the woman in the equation, that they feel comfortable enough to date whomever they wish. For most men, however, their women are like their cars, just one way of how they compete with other men.
And to be fair, lets face it. Women look for money. Men rate women based on her looks and women rate men based on their wallets. We'd all be happier if we looked for people who are good matches based on personality and character.