I had a flat chest in my teens and twenties
But I had my period and pubic hair on schedule
I started having boobs in my thirties
Now I wear a size d cup
To woman of 18 "and pretty much flat chested" ;o)
Well, yeah you are making it a little bit embarrassing - not because of your breast size, but your boyfriend is surely thinking he is doing something completely wrong, if you do not love him to see you naked.
I'm sure he doesn't blame you, but himself. It's part of all erotics (although this is never said and maybe not even realised) that the woman herself does not really see that she is attractive. She wants to be, but of course she is not attracted to herself ;o) and maybe she has been thinking in front of the teen mirror, that "oh, if was more like that person, then perhaps I would be!"
And the guy is almost embarrassed, because first of all he thinks that having her naked body close would take away 100 years of loneliness in an instant - which makes him sort of dependant, and that is embarrassing - and secondly, he feels a sacred calling almost to tell her how nice she is ... and that is even more embarrassing, because as soon as he has thought that, he also thinks: "Don't be ridiculous, she surely knows, and would just find it redundant!" - or maybe if she has somehow already proclaimed to the world (don't know if you have) that is not satisfied with her looks, then he can still be overcome by doubts, like: "Who am I to demand, she should feel good just because I think or say she is nice."
And he becomes completely confused, and blames himself alternating for thinking he should, and for not having done so already ... or whatever. But remember 18 year old boys are confused too - especially about girls ;o)
But the good news is, you're 18 - that's in between when we (a "pretty much flat chested" girl and I) first didn't make it work: every time my hand would get even close to the desired area, she would freeze with her arms crossed over her chest ... and I felt like an id**t, for not knowing how to handle it. (Normally you got to touch a girls breasts after a few beers and agreeing with that a certain teacher was indeed stupid, and that the Universe was definitely big ... huge even ;o)) But exactly this time, when it all seemed extra important, special, interesting ... whatever, the gate was locked.
That was 16/17 respectively. But early 20s I looked her up and tried again. This time I had gotten more brave. I didn't even want to know whether or not she had or had had a breast shyness, just wanted to be so strong that she wouldn't listen to anybody but me on this ... not even herself, but definitely not anybody else. Even though I was sort of atheistic, I had been to see God himself, and had told him; "Look, if you made a rule that a super small breasted woman can't be happy, I demand that you change that rule! And I am not going away, until you do, either ..." (well, not literally, of course, but that was the mode this time). And of course, he said he had made no such rule, and to just go ahead ;o)
I should perhaps say this to him, rather than to you ... but of course a woman has great powers to make a man brave, if he understands that she appreciate it. So you probably could do something, so you two don't have to wait until your 20s to get it all working beautifully.
Why are your breasts not inferior to large ones? Well breasts are loveable because of two things: they want to express something beautiful, to give - and they enjoy being appreciated. That is what makes any breast of any size something living and special - so forget for a moment please the "old if I was like her, then maybe" syndrome, and quiz your breasts if that isn't exactly what they would like, both those two things?
If it is true, then you will know that your breasts are lively and loveable ... or at least you will be open to that they might be. Small steps are fine.But those tons of feelings that your breasts hold, are like the water in the river.
The river is something because of the water in it.
Saying that large breasts are better than yours or contain more of those feelings that make breasts nice, is like saying there is more water passing through where the river is wider. It may look like that at a superficial glance - but at closer inspection you find that that is not really true. It s the same amount of water the flows through - but, and that's where breasts like yours can even seem extra attractive: through the narrow passages, the water just flows that much faster, and gets more oxygenated and so on. So what you can do with your breasts, is exactly the same as a large breasted woman can. So it can easily seem like your "river" is flowing more powerfully.
I'm sure he is desperately yearning for you to let your river loose ;o) and enjoy him seeing you naked and all that. And of course that is possible.
Perhaps you can do, not so much as the western fairytale princesses who pretty much just sit in an ivory tower, waiting to be saved. But be more like a chief's daughter form Aboriginal myths ... if there was a test to win "her and half the outback" (or whatever), she would sneak out and rig the test a little bit, to make sure the right person would win ;o)
I'm sure you need a little extra ... like feeling he is very intensely appreciative of everything about you, and not just "doesn't matter cause I love you"-ish, right? And he surely knows he will have to do the work and pass the test, but you could always rig it a bit, so it doesn't become impossible for him ;o) Could just be to show a little appreciation for being liked, or not demanding to wear your overcoat at all times, or some little opening to if he does something genuine.
// Gosh that was a long story. Hope some of it made a little sense ;o)
In my eyes and many other guys eyes small breasts are just as nice as average or large, it not the size of breasts that make a woman beautiful and desirable it's the person she is that does that and if you want my honest opinion I would rather have a woman with small breasts as I find them a big turn on.