How do you deal when you are overpromising and underdelivering due to really shitty unpredictable codebase? Im having 2-3 bad sprints in a row now.

For context: Im working on this point of sale app for the past 4 months and for the last 3 sprints I am strugglig with surprises and edgecases. I swear to god each time I want to implement something more complex, I have to create another 4-5 tickets just to fix the constraints or old bugs that prevent my feature implementation just so I could squeeze my feature in. That offsets my original given deadlines and its so fucking draining to explain myself to my teamlead about why feature has to be reverted why it was delayed again and so on.

So last time basically it went like this: Got assigned a feature, estimated 2 weeks to do it. I did the feature in time, got reviewed and approved by devs, got approved by QA and feature got merged to develop.

Then, during regression testing 3 blockers came up so I had to revert the feature from develop. Because QA took a very long time to test the feature and discover the blockers, now its like 3 days left until the end of the sprint. My teamlead instantly started shitting bricks, asked me to fix the blockers asap.

Now to deal with 3 blockers I had to reimplement the whole feature and create like 3 extra tickets to fix existing bugs. Feature refactor got moved to yet another sprint and 3 tickets turned into like 8 tickets. Most of them are done, I created them just to for papertrail purposes so that they would be aware of how complex this is.

It taking me already extra 2 weeks or so and I am almost done with it but Im going into really deep rabbithole here. I would ask for help but out of other 7 devs in the team only one is actually competent and helpful so I tried to avoid going to him and instead chose to do 16 hour days for 2 weeks in a row.

Guess what I cant sustain it anymore. I get it that its my fault maybe I should have asked for help sooner.

But its so fucking frustrating trying to do mental gymnastics over here while majority of my team is picking low hanging fruit tasks and sitting for 2 weeks on them but they manage to look good infront of everyone.

Meanwhile Im tryharding here and its no enough, I guess I still look incompetent infront of everyone because my 2 weeks task turned into 6 weeks and I was too stubborn to ask for help. Whats even worse now is that teamlead wants me to lead a new initiative what stresses me even more because I havent finished the current one yet. So basically Im tryharding so much and I will get even extra work on top. Fucking perfect.

My frustration comes from the point that I kinda overpromised and underdelivered. But the thing is, at this point its nearly impossible to predict how much a complex feature implementation might take. I can estimate that for example 2 weeks should be enough to implement a popup, but I cant forsee the weird edgecases that can be discovered only during development.

My frustration comes from devs just reviewing the code and not launching the app on their emulator to test it. Also what frustrates me is that we dont have enough QA resources so sometimes feature stands for extra 1-2 weeks just to be tested. So we run into a situation where long delays for testing causes late bug discovery that causes late refactors which causes late deliveries and for some reason I am the one who takes all the pressure and I have to puloff 16 hour workdays to get something done on time.

I am so fucking tired from last 2 sprints. Basically each day fucking explaining that I am still refactoring/fixing the blocker. I am so tired of feeling behind.

Now I know what you will say: always underpromise and overdeliver. But how? Explain to me how? Ok example. A feature thats add a new popup? Shouldnt take usually more than 2 weeks to do my part. What I cant promise is that devs will do a proper review, that QA wont take 2 extra weeks just to test the feature and I wont need another extra 2 weeks just to fix the blockers.

I see other scrum team devs picking low hanging fruit tasks and sitting for 2 weeks on them. Meanwhile Im doing mental gymnastics here and trying to implement something complex (which initially seemed like an easy task). For the last 2 weeks Im working until 4am.

Im fucking done. I need a break and I will start asking other devs for help. I dont care about saving my face anymore. I will start just spamming people if anything takes longer than a day to implement. Fuck it.

I am setting boundaries. 8 hours a day and In out. New blockers and 2 days left till end of the sprint? Sorry teamlead we will move fixes to another sprint.

It doesnt help that my teamlead is pressuring me and asking the same shit over and over. I dont want them to think that I am incompetent. I dont know how to deal with this shit. Im tired of explaining myself again and again. Should I just fucking pick low hanging fruit tasks but deliver them in a steady pace? Fucking hell.