IVF - The Emotional Roller Coaster

Tomorrow we go to see our IVF doctor to start the process of implanting our last embryo.
I'm not excited. I should be I guess. I know I should be all positive and all, but I just don't want to get my hopes up. Because this is our last go. Ever. And I don't want to come to that point when I have to accept that I will never have another baby.  I know that it will be painful at first and it will gradually recede to a quiet little corner that I will revisit from time to time. I know that the chance of not having another child was more likely to happen. And I fully knew before I fell in love with my husband that it would be a hard process if not impossible when we did decide to try to get pregnant.
I don't know how to describe it. Being a Mum is what I know I was put on this earth for, and I love being a mum to my son. I always thought though, that when I met someone I would have more kids. I don't blame my husband. He can't help what happened in his childhood, and I'm sure if he could do it over again (without the leukemia, chemo and drugs) he would do it in a heartbeat. I knew all this when we first met. But you can't help who you fall in love with, and I wouldn't change that at all.
I guess people would say be happy with what you have. Well I am. But is it too much to ask for just this one more thing? I'm a good person. My hubby and I are great parents. Why should all the deadbeat parents have children that they abuse or ignore, and send to bed hungry, and to school with no shoes. Then I get all mad at myself for thinking these things. For being all negative, because I've got to be positive right? I've got to will this to happen. What if the last one didn't work because I wasn't in the right frame of mind? Do I sound like I'm rambling and confused? Yes I do, but these are some of the thoughts that go through your head when you are going through this emotional roller coaster of IVF.

I guess I'm just being a hormonal female at the moment. I hate feeling this way. Hopefully I'll come away from the appointment tomorrow feeling more positive.