I’m the same size and age with concerns about looking thin and frail. Here are some things that have helped:

1. Passage of time postpartum. After each of my kids, I looked especially gaunt for about a year and a half postpartum. My guess is bad sleep and breastfeeding. But after consistently getting better sleep and stopping nursing, I gained a little weight and started looking more lively again.
2. Weight lifting. Like others have said, this this will help you look, feel, and be stronger. Programs designed for women may be especially helpful since you had a baby last year.
3. Tucking in my shirt. This is so simple it feels silly, but it has really made a difference in making me look more put together and less gangly.

Anonymous wrote:I am thinking of off-setting my thinness by getting a bigger bust. I definitely can see the allure adding weight to that area only.

They will look obviously fake.

Anonymous wrote:You are not that thin…

I weigh 130 at that weight and I'm a size four.

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:Definitely strength, if nothing else to reduce risk of osteoporosis. I'm 5'8 and 125 so probably similar (if that "5lb per inch rule" is valid), and I definitely don't look too thin. I do have a boy-ish figure (no curves), but not a lot I can do about that. Lift heavy!

Way too thin, skeleton like probably

It's appalling that women with a normal BMI still get body shammed by women like you in this "all bodies are healthy/beautiful" culture.

Lol. I’m sure you never have a bad thing to say about any larger bodies. NP.

Nah, I don't care how large you are.

Anonymous wrote:I am thinking of off-setting my thinness by getting a bigger bust. I definitely can see the allure adding weight to that area only.

...because you are a man.

Anonymous wrote:If you have a kid under a year or 18mo, give it a bit of time. I have noticed that naturally slim people tend to look like their babies sucked the life out of them until 6-12 months after they wean.

Strength training while eating enough protein.
Play with proportion- wide leg pants with an tailored top, chunky sweater with slimmer trousers.

This is true in my experience. And I barely breastfed. I feel like it just took a long time for my metabolism to reset from hormonal weirdness. I'm also a runner and cyclist and those tend to make you look starved if it's all you do.

If you have a kid under a year or 18mo, give it a bit of time. I have noticed that naturally slim people tend to look like their babies sucked the life out of them until 6-12 months after they wean.

Strength training while eating enough protein.
Play with proportion- wide leg pants with an tailored top, chunky sweater with slimmer trousers.

I am thinking of off-setting my thinness by getting a bigger bust. I definitely can see the allure adding weight to that area only.

5’3, 112 and 20 bmi here. I stepped up my weight training over the past few years and it had made a huge difference to me at least in my confidence and other people have commented I look better. I still weigh little, but look less frail.