Modding AI is the most difficult task in SE. The best way is to study the files ofthe best TDM races and learn by trials and errors
How to you load your race ? If you generated .emp file before changing fleet.txt file, AI will not use it. Come information is stored with empires. AFAIK it includes settings.txt, strategies.txt, fleets.txt and anger.txt files. Other files are read by AI at the beginning of each turn. If this is the case, scrap .emp file and generate a fresh one. For this purpose start new game with large number of random empires and you playing some other race. In game pulldown check "races" and see if the race in question was chosen. Switch it to your control and save empire. This way it will record modified files.
If this is not the source of the problem, there must be some error in your fleets and/or strategies files.