I'm 15,I basically know everything there is in need to know about maps transport etc... I have passport to enter countries,I talk 6 big languages English,Russian,German,Spanish,Italian and French and Maltese my native language.I won't have enough cash because I would be 18 by the time I will leave.I plan to spend my life traveling the world by foot and eat what life offers.Any suggestions or help?

Stay occasionally in convents and monasteries when you need to sleep. You can look this up online and sign up there.

Once you turn 18, test your ability to walk, and keep on walkng, by walking one of the Camino de Santiago pilgrimage routes. You coild walk the Camino Frances from the french/Spanish border to Santiago de Compostela, a total of 800 kms on a well defined track. Or, if your feeling strong, walk to Compostela from Paris. If you succeed in this, and people do it every year, then you will know you can cope with walking just about anywhere. Jut Google Camino de Santiago for more information.

omg by foot dont do it

it will never work.