Hello people!

I've always been a huge sucker for tooth-achingly sweet love stories but I don't know where to search for them, so I'm turning to you instead!

What I want is a female lead with a cute/lovable personality and a male lead with a warm heart. I don't want there to be any doubt that the main couple won't be together and it'd be a plus if they were clinging on to each other ^^

If you find it hard to match all of these criteria with one particular show, just bomb me with any other show you find incredibly sweet!

This has been Timothy

Peace!

Hi!! Well some of the dramas I'm gonna recommend won't 100% fit your criteria but I liked them all..:) so I'd recommend..

Asuko March! 
Beautiful Life ---> melodrama though..
Buzzer Beat
Doctors --->  a strong female lead
49 Days ---> again another melodrama...but it's one of my favourite dramas.
Kingyo Club ---> short and sweet!! ^-^ 10 eps and each ep is just 20 mins..

If you don't mind movie recommendations as well..

Virgin Snow
Hear Me
Bangkok Traffic Love Story
Kimi ni Todoke
Orange
Oto-na-ri ---> a bit slow but I loved it
Close Range Love
Summer, Whispers

I hope you enjoy!! :) :) 


Korean:
High School King of Savvy

Chinese:
Boss & Me

Taiwanese:
Bromance

Japanese:
Koe Koi
On the Way to the Airport (k-drama) is not sweet every second of it but the female lead is very lovable and the male lead has a very warm heart. They sort of fall in love at the first moment even though they don't exactly fall into each other's arms right away. The drama is very lovable and gives you a warm and fuzzy feeling overall even though there are sad moments. You never doubt their love. 
First thing that came to mind when I read "tooth-achingly sweet" was On the Wings of Love (Philippine drama). I haven't completed it fully (I'm halfway) but it fits most of your criteria in my opinion. I think I'm going to go and watch a few more episodes now that I'm thinking of it lol xD
I see that it's already on your plan to watch list but the first thing that came to my mind is Love O2O. 
flower boys next door
exo next door
Hi ! The dramas that I am going to recommend won't fit your criteria but at the same time , they are amongst some of the sweetest dramas that I have watched :

Shopping king Louis 
Full house (Thai)
Oh My Venus is a fave and I find the romance super sweet
Love Sick: The Series Season 1 & 2

Season 2 was definitely an overload of love between Phun and Noh.
One movie with a love story that I adored is "The Beauty Inside." It has a sad undertone, but the couple is very clearly in love and the male lead is very sweet.

As for dramas, Oh My Venus was relationship goals too.
Weightlifting Fairy Kim Bok Joo
Shopping King Louis
Lucky Romance

FLUFF OVERLOAD
absolutely adorable lead couple
I second on Weightlifting Fairy Kim Bok Joo and Shopping King Louis!! you should really watch it!!! totally sweet and cute and fluffy and funny :3
Looks like you've already watched WFKBJ  and SKL. I'll recommend Something about 1% (the 2016 version), will second Oh My Venus, add Queen In Hyun's Man, and throw in Healer, which maybe doesn't completely fit the bill, but the romance may.