BMI is 18.5 ...how can I gain some weight healthily?

[again2020]

I was on a diet early this year and lost around 2 stone going from 10st 4 to 8st 6. I wanted to maintain at around 8st 10 and I admit I took it too far.
However after a chest infection last week where I lost my appetite I was shocked to find I'm down to just over 8st 2. At 5'6 this means by BMI is 18.5/6.
I'm too thin. People have made comments. I've lost all my bum and boobs 😔 I'd like to gain about half a stone.
The problem is, how I see food has changed. I'm just not as hungry anymore. I'm very conscious of eating too much sugar. I used to constantly eat biscuits and cakes.
How can I gain weight in a healthy way?
For breakfast I've had a banana, a slice of white toast with margarine and some jam, some pineapple juice and a coffee. This already feels like a lot of sugar. I'll probably go to softplay with my DD and have a sandwich there for lunch but it's probably very fatty.
What can I eat to up my calories? Would protein shakes help? I'm vegetarian and drink mostly plant based milk by the way.
Thanks.

What about adding in some full fat Greek yoghurt, avocado on seeded toast, handfuls of nuts, etc? You can eat good fats which will help with calories rather than relying on sugar. You’ll hopefully find your appetite increases as you start to eat a bit more.

Have a low threshold for seeking help if you’re struggling.

What are you eating at the moment? That might help with where to suggest making changes.

@PurpleDaisies Thank you! I'm going to have some nuts this morning.

I eat 3 meals a day but breakfast and lunch can be light. I might just have yoghurt and fruit for breakfast and an omelette or sandwich on one piece of bread for lunch. Unsure what to have as healthy snacks rather than just eating biscuits, but nuts are a great idea.

Peanut butter
Full fat Greek yoghurt
Real butter
Cheese
Nuts

I'm similar, trying to gain some weight. I've started making banana and peanut butter smoothies which is helping.

Eat more protein.

Nuts as a snack
Have peanut butter on toast instead of jam and marge

Hoummous. Really easy to make your own and cheaper per batch, the expensive outlay on the tahini lasts ages. Have it on toast, in a wrap or pita with falafels (Lidl often do good frozen felafels, I keep a bag in the freezer)

Banana sandwiches. Or banana and peanut butter.

Also, do toning and muscle building exercises to fight the ‘thin bum’ look.

Adding a second slice of bread to your sandwich would be a good idea. Sprinkle cheese on your omelette. Pine nuts in a side salad.

What’s in your dinners?

You need a combination of healthy fat and healthy carbs but fairly low protein and just your normal amount of fibre. You are really aiming to gain some bodyfat, not muscle so that's why I say not too much protein. Protein is very filling so it curbs your appetite which you don't want. Eating fat and carbs together is the best thing for gaining bodyfat.
So basically add some extra healthy fat any time you eat carbs. Eat your regular amount of fibre and protein but don't add lots of extra.
With the menu you gave I would make sure your yogurt is full fat and choose a higher carb fruit, lunch add an extra slice of bread and butter and some cheese to the omelette maybe an extra egg in the omelette, or choose a higher fat but healthy sandwich filling with 2 slices of bread for dinner your normal dinner but increase your carbs a bit and add some fat for example if it was curry and rice have a few extra tbsp rice and add some extra butter and full fat yogurt to the curry.

How’s today gone for you @again2020?

Sorry for delaying in replying.
Thank you to everyone for suggestions.
Been eating 2 wholemeal pittas and hummus for lunch this week and enjoying it, as well as more fruit and have gained 0.5kg! Happy with this

My BMI naturally settles around 18.5 - have had to up it twice for fertility treatment.

I drink a lot of whole milk (organic because I think it’s marginally less indefensible welfare wise) which is out if you’re plant-based for milk, but other stuff I tried was…

No cardio at all (not great long term but works for a short while)

Pour olive oil on everything

Eat before bed as well as at tea time (I usually have dinner about half 5 then breakfast 7ish the next morning which I think prevents weight gain)