Is it possible for a guy to be transsexual lesbian or transsexual homosexual and know only the transsexual part?

Yes, it's possible: A person's understanding of their gender identity (male, female) should not be confused with their sexual orientation (sexual interest in males, females, or both). It is not uncommon for people to go through periods of uncertainty or confusion about one or both of those issues, particularly if they feel they cannot safely disclose and discuss their feelings with family or friends.

Yes: Gender is your sense of identity (male, female, nonbinary, etc). Gay, straight, bi, etc refer to sexuality- who you are attracted to. It is quite possible to know one, but still be figuring out the other.