Whether already existing people like life is like asking whether already addicted people like heroin. You can't use the result to justify forcibly addicting people to heroin.
Disclaimer: you're free to believe what you want, and it's neither my business nor my concern whether or not you pass on your particular genes, I just can't resist this discussion.
Related reading if you're interested: Albert Camus (The Stranger, The Myth of Sisyphus), Sartre (Nausea, Being and Nothingness)
You say it's not your business whether or not I pass on my genes. Is it also not your business whether or not I murder somebody you do not know? Creating new persons is not something to be taken lightly, it's at least up there with murder because birth entails death.
By all means realize the absurdity and seek contentment, just don't force others into having to come the same long, stressful way to this revelation.
As I said before, the question of whether I should stay alive even if I don't think it is worth it is way more complicated than the question of whether new lives should be begun. One complication is that suicide causes non-negligible stress for both the suicide and their surroundings.
Let me first tackle the philosophical level: First, you insist on the impractical notion that it is only the suffering that counts and must be reduced no matter what. Being a intelligent fella you realize that the consequence would be the annihilation of all sentient life including your own. Since presumably you realize the absurd notion of this consequence you try to reclaim the validity of your argument by arguing that “not forcing others” is another crucial prerequisite in your ethic. (Regarding your own suffering and the ending of it you simply declare that “life is complicated”. Aha, so much for consistency. (By all means: be inconsistent in that case.)) But strictly speaking, you cannot force life on someone because that someone does not exist before she is alive. You can see it in your own comments. You talk about “forcing life on newborns”. But this is not true. Before they were alive they simply were not there. By definition you cannot force something that does not exist. Again: I can force you to give me your money but I cannot force something nonexistent to do anything. So you are back to square one: total annihilation of all life.
The same reasoning applies to your heroin addiction analogy by the way: The alternatives are not heroin vs. no heroin but heroin addiction vs. death. You see, you can without a doubt compare a person that is heroin addicted to one that is not and conclude the the non-addict is for some reasonable metric better off. But you cannot compare a person who is alive with something that does not exist. It doesn’t make any sense.
The philosophical nitpicking aside, what really strikes me as odd is your sole focus on suffering. In your picture you also “force the newborn” with high probability to having two legs, in- and exhaling air, and opening a bank account before her 30th birthday. And who likes that? But wouldn’t it be much more reasonable, as other commenters have pointed out, to account for more than just the suffering in the calculation whether a life is worth living? When you are in need for something, lets say food, do you only take into account the costs or do you compare the benefit you get from the food vs. its costs (the costs being the suffering in this analogy)? I mean, as a “life addict” yourself you realize that the suffering is sometimes not everything that counts especially when it is outweighed by the benefits you have by being alive. Don’t get me wrong: of course suffering is bad. But as you said yourself “life is complicated” and often you have to take more into account than just one single variable like suffering or the opening of a bank account.
It is of course your choice whether you procreate or not. But your argument against it might not be as conclusive as you might think.
Regarding "forcing" someone into being: you have a problem with my words, not with my reasoning. As I said, birth can be a harm because the victim is still around to suffer its consequences. Death or "never being born" cannot.
Most people disagree that people can't be harmed by birth. Women are rather sternly discouraged to use alcohol during pregnancy. It is frowned upon for people with any significant genetic problems to reproduce. Incest is also taboo. Many people would think it better if the poor would not have kids. This has no bearing on the truth, of course, but I would be surprised if you didn't make similar judgments. It is clear that there are at least some cases where pre-existent beings' future well-being is taken into consideration.
The question then becomes "where do you draw the line?", and reason would draw it where I do (at "nobody should procreate"). The idea is simple, if you're willing to suppress your inner pedant: those who are never born do not suffer and they do not miss out on anything. This is the bottom line, and all the pedantry in the world won't change this fact.
The only case that could -- MAYBE -- be made is that if the kid's life turns out just fine, it wasn't too bad to create him. Just like an attempted murderer could say, of his surviving victim, "sure I tried to murder him, but look -- the dude's doing fine!". Things may have turned out alright, but I wouldn't say that attempting to murder a person is acceptable (beyond the intentions involved).
If I gave you a wheelchair, you might ask me what the hell you need a wheelchair for. Only after I have gnawed off your legs will it make sense. Before this, you had no need for a wheelchair. Similarly, the unborn have no need for a life that turns out just fine.
Procreation is never in the interest of the newborn. Suffering is guaranteed. Happiness cannot be used as a justification. It's all there, isn't it?