I failed to choose the right keywords

Start buying keywords from sellers on BHW then see how it compares with what you have been doing.

Seems like you're not clear with the concepts of On and Off Page SEO. Look into On Page first, read a few guides. Choosing keywords is not easy and most sellers here will rip you off with shitty keywords. You need to slow down and read more, look at case studies and check out the journey section ask questions etc.. I'd recommend closing down shop and spending some time on the forum, at least 45 days checking out different threads before you take action.

And the mistake you made is not uncommon. I did the same thing the first time around, chose impossible keywords. A lot of people do that starting out. Cut your losses and start learning. You'll be able to find good Keywords in no time.