Can I get some advice about health worries?

I'm 17 and neither I nor my 15 year old brother have ever been taken to a dentist or a doctor for checkups. It's not one of those stories where the parents just can't afford it - in this case they just don't care. Honestly, it really really bothers me. Many people complain about appointments or otherwise talk about seeing a doctor as if it were a piece of cake, and it makes me feel bad because I don't have the option they do. It also makes me very insecure because I don't know if anything could be wrong with me, or if all these years of being without health care will affect me later. Basically I feel filthy and undeserving when I'm around people who have had parents who cared, and I'm afraid people will find out about me. I've also lived in a roach infested house probably my whole life and it makes me feel awful because even though there's nothing I can do about it personally, it makes me feel like there's something wrong with me, like I'm dirty. That's just a short summary of how I feel about it. But the biggest thing about all of it that I need advice on is this... I don't know HOW I should decide to feel. I believe strongly that your attitude will ALWAYS influence your life the most, regardless of your cirstances. But I feel like I've been handed some very bad cirstances when it comes to a lot of things, and I understand now more than I did when I was younger that my parents have neglected my brother and me in many ways. I just don't understand why it's had to be that way, and I want to know why. But I know many people have flourished in very bad cirstances, and I know I can too. So is that what I have to do? Because I know that if I am less healthy than the average person (whatever that is) then worrying will only make it worse