My (26F) best friend's (26M) girlfriend (23F) keeps telling me I'm huge but I'm the same size as her

This is such a dumb problem I feel stupid for even bringing it here, but I'm just at my limit.
My best friend Mark (26M) started dating Allie (23F) a few months ago. He seems very happy with her and very into her. So far all good. He introduced me to Allie and she seemed nice. I noticed she had a very cutesy style of talking and acting, almost like she was a Disney princess. I figured that was just who she was and didn't think much of it. Some people are just naturally cute.
Allie likes to bring up how tiny and thin she is a lot. Like a lot. She'll work it into any conversation. We're talking about hobbies? Allie has always wanted to take up volleyball but she's too tiny to reach the ball. Clothes? Allie has trouble when shopping because she's so tiny she can never find her size. Kids? Allie's scared to give birth because she's tiny and the baby will rip her apart.
I privately found it kind of funny because Allie is not really tiny. She's not big either, she's just normal. In fact, she's basically the same height and weight as I am, if I had to guess. I'm 5'5" and Allie is exactly the same height as me, and she looks like she's probably a similar weight (I am around 124 lbs) too. I wouldn't call myself tiny, I'd just say I'm average. But I don't care if Allie likes to call herself tiny so I just shrugged and let it go.
Except then she started saying not only is she tiny, I am huge compared to her.
And she said it a lot. OP, can you get this off the shelf for me? I can't reach it but you're a lot taller, so you can! OP, that skirt is so cute! I'd ask to borrow it but you're a lot bigger than me so it wouldn't fit. OP, I've never noticed how big your hands are! OP, we look so funny standing next to each other, it's like Little and Large! OP, are your family Scottish? You have big Scottish bones.
The first few times she did this I smiled and said we're basically the same size and height, aren't we? Except Mark cut in to tell me that no, I'm much much bigger than Allie, Allie is TINY. Tinkerbell herself come to life. He even put his hand on top of Allie's head and then drew it across to mine to show me how much taller I was, except his hand took a sudden jump up and hovered several inches above my head like the top of my head was invisible or something. It would have been funny if it wasn't so weird.
Now he's getting other mutual friends of us in on the act, so I'm constantly hearing about how huge I am and how teeny tiny a woman the exact same height and weight as me is. It is insane. I am starting to question if I have some weird case of body dysmorphia and I actually am much bigger and taller than the scale and mirror say I am.
I am tired of this. How do I get Mark and Allie to stop it? I don't want to lose my best friend over this, and I also don't want to be seen as the weird girl who gets offended over something so dumb.
TL:DR: Best friend and his girlfriend keep telling me I'm a giant hippo and she's a dainty fairy. We are the same height and weight.


Source.

It can be hurtful and hurtful when someone makes negative comments about your body, especially when those comments are not true or are not based on facts. It sounds like your best friend's girlfriend is making hurtful and unkind comments about your body size, which is not okay. It's important to remember that everyone's body is different and unique, and there is no one "correct" size or shape.

It can be helpful to talk to your best friend about this issue and let him know how his girlfriend's comments are impacting you. He may not be aware of the comments she is making and may be able to speak with her about it. It's also important to surround yourself with people who uplift and support you, rather than tear you down.

It's also important to focus on your own health and well-being, rather than comparing yourself to others. It's important to remember that a person's worth is not determined by their physical appearance. It's important to practice self-care, self-compassion and self-love, and to surround yourself with people who will support and encourage you.

It's important to remember that you are the best judge of your own body, and you have the right to define what is right and wrong for yourself. It's also important to have a positive self-image, and not to let anyone's comments to affect your self-esteem.