Clothes make the (wo)man
Yes, clothes are used for expression of who we are. A favorite character, a funny saying even to memorialize a loved one, but do clothes really state your sexuality. To be honest the answer to that is not as black and white as you may think.
While it's true that crossdressing has been linked to homosexuality, the two actually do not go hand in hand. While there is no hard statistics on the percentage of gay crossdressers vs straight crossdressers the fact is that there are a multitude of reasons to crossdress. Typically though the reason may revolve around something other than sexuality.
Comfortability: For some it may just be more comfortable. Some crossdressers don't even fully dress. They might only wear panties or even just shoes because they are more comfortable in them. If you go fully it's still the same that you may feel more comfortable. Same can be said for women wearing mens clothes.
Occasional: There are some who are only feel the need to do it on occasion. Perhaps only on Halloween or they may have specific times during the year set aside for it.
Fetish: It is also used as a fetish. Some heterosexual couples do enjoy this type of fetish. Everyone has something that turns them on and even if not everyone admits it, we all have at least one fetish.
Just to name a few and it is possible to have more than one reason for doing it. This is not to say that all crossdressers are straight or that they don't do it because they are gay and want to be the girl. This is just to show that these are two different things.
Is there gay clothing?
Obviously clothes don't have a sexuality. While it is that society has a mindset that particular clothing is connected to our sexuality, the end result is that we wear what makes us happy. There will always be people who are one track mind when it comes to this and while there is no hard answer to these questions the final answer really comes down to you.