1. Is 19 too late?Starting transition at 19 is a good age. You do have some advantages at that age. You're adult, something that might give you more opportunities and nobody in your family can refuse you transition. You're old enough to take your own decision. You're still young and in my opinion transition is pretty much safe and effective before the age 30. But there are also many people who's 30+ with successful transition. Even you have been through testosterone puberty, you can still make it work, you're young.
2. I have really hairy legs, is this bad?HRT would decrease your hair growth. But waxing, shaving, electrolysis or laser can also be some opportunities which might work for you.
3. I don't have lots of money, will this be a major problem?If you get a good job, insurance (If you're from the US) and saves money, the problem might be solved. You can also receive donation if you want to from friends etc. If you gets money as Birthday and Christmas presents, that might also go to the transition fund. Haircut, clothes, shaving tool etc wouldn't be too expensive. It exist HRT which isn't too expensive too. The surgeries and electrolysis is often the most expensive ones. Good insurance might help.
4. I have big feetPeople usually doesn't stare at other people's feet. It's a bigger chance people would look at your face than your feet. Feet isn't the biggest worry you need.
5. I am really skinnySkinny is fine. It's harder to get rid of masculine muscles from what I've seen, as long you hasn't super big muscles there wouldn't be any issues. Skinny is usually not a issue and you would get a more feminine body shape including softer features with HRT. You might also gain some weight with HRT.
6. I am quite tall.There are also tall cis women. Some of them also works as models. As long you have a feminine face and attitude, it's lower chance people being suspicious.
7. My hair doesn't grow very long (was considering wig)There are many good wigs in this world, so if you feels more comfortable with wigs, go for it. It exists wigs which looks natural/realistic and is made of real human hair. They are expensive, but perhaps worth it. If you want to buy wigs, I recommend you to own two. It's smart to have a extra wig just in case some of them gets worn. You have to replace them with new ones sometimes too.
8. I just feel that my expectations are far too high of how i will beIf you looks at other people (medical) transition, you might get a idea how effective HRT is and perhaps a more realistic pictures. But keep in mind every people are difference, so I doesn't recommend you to compare too much to other tg people. You may get a image how it works with looking at others.
9. I feel selfish for doing this, as I devote my life to helping others, I don't like helping myself.
Can I get some help with how to act and joining the community of LGBT.It's not selfish at all. If taking care of your health should be considering as selfish, then wearing glasses, going to the dentist, taking medicines etc. should be considering selfish as well. It's not your fault you're in this situation. Trying to do the best out of it and making yourself happy is a good thing. Don't let other put you down.