Sometimes I sit here and I wonder that maybe the purpose that I have so willingly succumbed to wasnt a purpose at all

If you assume that a willingness has no purpose, then perhaps you have entered into
a domain that is fresh and new; intimidating and yet inviting... ergo theri is a purpose yet unknown.
　
I tried so hard and then so little.... only to find that my inadequacy was only my own failure.

Inadequacy is not failure...and it is often misunderstood as misplaced loyalty; insufficient experience or knowledge.
To try hard... and then so little is a wise choice... provided you have not given up... but instead; you have stood back, prefering innaction rather than persist to where you falsely accuse yourself of inadequacy, and consequent presumed failure.
Only a foolish person will persist with inadequate knowledge or experience... a wise person will step back.. preferring innaction... allowing time and circumstance to present itself... before stepping forward again.
Do not presume that innaction.... to try so little... is an inadequacy that leads to your failure.
　
I find myself having no time for anything but having an immense amount of time, for everything.

If you think have an immense amount of time for everything... it is easy for you to presume you have no time for anything.
Do not measure the sum of your tasks with apparent limitless time. To complete any task...measure the value of the task first with it's importance... then with the tools required... and only then... assign the concept of time.
A task is only done well... done adequately.. and with satsifaction... if you assign these concepts.
　
Will I always be this completely selfish giver constantly riddled by only my own endeavors?

It is not selfish to attend yourself... but when we exceed our given and presumed abilities.. our endeavors appear inadequate... unfinished... and received with disdain and suspicion.
And so we blame oursleves... we presume we are selfish... that we should not attempt any task at all... for it will fail.
To give is a blessed task... a valuable asset... to give without exceeding who we are... how we wish to be seen... without regard or consideration of reward or remuneration... is to give without exceeding the sum of our capacity.
We are often asked to exceed our capacity... we often inadequately interpret such a request... in that we attempt many tasks... expect more than we need from others... assume we are infallible.
And so we wonder if the the purpose for which we presumed we have an immense amount of time... has any purpose at all.
We find that in reality we have no time for anything ...wherein we presumed to have time for everything.
We become selfish in that we can no longer satisfy the many masters we wish to serve in order to verify our presumed purpose.
And so we propose that we have... we will fail.
If we fill our mind with many tasks... and try to complete them all at once... rather than in order of our preference for the importance of each task... you will quickly find that all the time in the world is not enough time to complete even one task.
In choosing a task wisely... do not exceed the capacity of your hands to build... the time to compose a thought; to write a letter; in that you attempt all at one time, in order to satisfy many... rather than first attend whom you consider of most value..... in most need.