If you're really transsexual those thoughts never go away, no matter what you do. It's up to you to accept yourself for who you are. Only you can decide whether you're trans or not. But you need good information to make your decision from. Here's some:
http://t-vox.org/information/transgender-transsexual/trans-101
http://t-vox.org/information/transgender-transsexual/i-think-im-transsexual
http://ai.eecs.umich.edu/people/conway/TS/TS.html
Does that describe you?
Do they fill you full of bubbling ideas, or do they make you want to run away?
Lastly, the acid test (WARNING: Graphic surgery pictures)
http://www.garyalterplasticsurgeon.com/transsexualsurgery/Examples/trans_mtf_examples.htm
Does this make you want to book a bed, or does it make you clutch Mr Happy in sympathetic agony and run away?
If your answers were "not run away", then you may be trans. If your feelings are giving you trouble in your daily life, then you'll benefit from speaking with a gender therapist. Here's a list:
http://www.drbecky.com/therapists.html