Drama where female lead is timid, lacks self confidence/self worth or is lonely/longs for affection

• Wednesday 3:30 PM - FL lacks confidence / is insecure. I don't remember exactly when each of them fell, but I think the FL fell first. The FL is trying to make her ex jealous but he's not really a love interest and definitely never creates a risk of SLS. There is a F/M/F love triangle.
• My ID is Gangnam Beauty - The FL meets your criteria. My interpretation is that the ML falls first. The ML was the most attractive boy at the FL's middle school and she never disliked him, but I think the possibility of dating him never even occurred to her because of her insecurities. But it's a little vague and open to interpretation iirc. There's a second female lead who pursues the ML and a second male lead who pursues the FL. The SML is likeable, but the ML is also great. I didn't get SLS.
• A Piece of Your Mind - I don't immediately think of the FL as fitting the description you gave (although  I could say the same for the FL from My Secret Secretary), but the drama fits your criteria. The ML and FL each begin to heal from personal losses through the course of loving each other, the FL falls first, I don't recall any SML, and there is sort of a F/M/F love triangle.
• A Poem a Day - FL lacks a bit of confidence and falls first. There's a SML but definitely no SLS. He rejected the FL in the past. 

Doctor John - I think this might fit what you are looking for. The FL lacks confidence within her job. Once she meets the ML she starts to gain confidence. No love triangle either

 Ollie:

Doctor John - I think this might fit what you are looking for. The FL lacks confidence within her job. Once she meets the ML she starts to gain confidence. No love triangle either

Thanks a lot, I'm a medical student myself so I'll definetely watch this one!

 Little Cherry:

I read somewhere that in "a poem a day" female lead loves the second male lead first but he rejects her continuously then she gets over him and falls in love with the male lead who's been in love with her from the start?

That means male lead falls first na?

Also, there is strong love triangle too, so I want to ask does female lead ends up with the one she likes? Or with the one who likes her?

Re: A Poem a Day

It's a love triangle between two males and a female. You won't have strong second lead syndrome, at least I didn't. I'd still consider it a drama where the female lead falls first for both of the guys (at one point in time at least) can't blame a girl for moving on. 

Basically, to give you an idea of the drama without ruining everything: one of her new coworkers was someone she confessed to a long time ago and he cruelly turned her down. He later starts to develop feelings for her but she already has feelings for one of the new doctors there and she pines after the doctor for a long time, but also starts to reconcile with her coworker.  

This drama is kind of like the Reply series where it kind of leaves you guessing who you think she might end up with. 

Your last question seems to indicate you want to know exactly who she ends up with, so if you don't. Don't read this: She ends up with the one she likes, the doctor.