Drama vs. Happiness

You know, sometimes I wonder if I do actually want to be happy.
I am fully aware of how weird that sounds, but its like I deliberately let things happen that I know are going to make me miserable. I justify it by saying that I'm helping out other people (re: unwelcome house guest) or sparing their feelings (re: not moving home for ages) and maybe that's genuinely what it is. I hope that's genuinely it of course. But sometimes I wonder if I secretly enjoy the drama so much that I deliberately sabotage myself. Or maybe I don't feel that I deserve to be happy, coz it damn well sure looks like I never will be.
This totally isn't coming out how I mean it in my head. I'm not being some sort of emo with this, not looking for attention or sympathy, I'm trying to work out why I find it so difficult to say no sometimes.
Ive said before that I'm always the person that people come to with problems, and like Ive also said, I'm absolutely fine with that, I do love helping people if I can. I want them to come to me, I want to be able to help them work out what it is they want or need, and I do so love giving them advice ;o) but I also love it as it takes my mind of mine.
I'm the kind of person that doesn't worry. My mum always said that if I was any more laid back, I'd fall over. When I had Lily, people would comment on how calm I was with her (oh how one more baby changes that!), but I don't see the point of getting worked up over things which you have no control.
When Ethan was a baby, he got really sick with bronchiolitis, yes, its a real disease, an inflammation of the bronchioles, and nearly died. He spent a couple weeks in a little oxygen tent (I have pictures somewhere, kept a little diary to try and keep my mind off things) and has since made a full recovery. But the reason I'm bringing this up is that when we took him to the doctors, my mum was practically hysterical, crying and stuff, demanding to know why I wasn't the same way. Saying things like "Why aren't you upset? Why aren't you worried?" Thing was, I was worried as hell, I was dying inside hoping that he was gonna be ok. But me getting all worked up and panicky wouldn't make him better. It wouldn't change his condition so I didn't. I comforted her and I looked after him. I did what the doctors said and he got better.
My point is, why waste time getting all stressed and worked up when that's not going to change anything?
Hmmm, this totally isn't where this post was headed when i wrote the title. I do actually wonder about myself sometimes. Why I do find it so difficult to say no.
I guess that's more of a confidence thing. Coz I actually managed it last week when I asked the HG to leave. Finally plucked up the courage to actually tell him Id had enough instead of waiting for him to be done and then pretending it was my idea.
That's a step in the right direction I guess. I just hope it continues to build this time. I was doing so well for a good while then I stupidly agreed for HG to stay again.
Hopefully Ill learn my lesson this time and say no if the situation comes up again. Its not my responsibility and I have my own life to lead.
Remind that its ok to put myself first sometimes please?