Hi,
I read your post and thought I would reply as I recognize much of what you are saying, but from the reverse direction. You have already had lots of good responses so I fretted about whether or not to post this because I don't want to influence you in any way; I'm no councilor; and I don't purport to be an expert. Hopefully I've been as neutral as I can be whilst still saying what I think – I've certainly tried.
Obviously I can't tell you what is right for you, but I can give you some of my thoughts and perhaps you can take something from them that is helpful.
The first thing I think I would say is don't accidently try to shoehorn yourself into any boxes. It's easy to read other peoples experiences and definitions of what it is to be FTM, MTF or whatever else and to recognize that you feel the same things and then before you know it find yourself subconsciously trying to fit their definitions.
FTM, MTF, bi-gender, two-spirited, etc - all of these are just words that people have come up with to try to describe what they see of the human experience. They're useful because they allow us to explain a type of person / experience in one word without an epic long description each time. But, they don't mean that a given person will perfectly fit into one of them, or that the definitions won't change as understanding evolves.
We are all individual, so listen to that voice in your head. Don't ignore that part of yourself that some days wakes up and feels more like a woman. I can't tell you if that means you should or shouldn't live your life as either male or female (or somewhere inbetween for that matter), but I can say I would hazard a guess that it won't go away.
It's ok to be a man and sometimes feel that you are more like a woman. Equally, it's ok to be a woman and sometimes feel that you are more like a man. Neither makes you not a man or not a woman and you can transition and feel those things or not transition and feel those things... try to make sure you explore all the different ways you can express yourself to see if there is something that fits for you.
Personally, I also don't think it means it is either more or less valid to transition or not, because I think it is all part of the normal breadth of experience of what it is to be male or female - I don't mean that every person feels those things, but that it is part of the normal breadth of human experience. (There is a tremendous amount of politics that comes into these things though and all manner of arguments that happen about what constitutes a 'real' this that or the other, lol.) However, that's by the by - I think what's important is to recognize and acknowledge all the thoughts that are happening in your head and not try to ignore any of them, as that will help you work out what is right for you... but you seem to be doing that anyway as you're writing about it.
One of the things you said was: "[...]every time I feel like a man, I keep thinking that I am not really one[...]". This and its reverse is a common source of insecurity for people who transition. If you read enough accounts by people who transition you will see that sometimes even the most 'passable' and well accepted people can struggle to reconcile their thoughts on that one. Different people resolve it for themselves in different ways, but ultimately I think the only thing I can say is that we all have to take responsibility for our own decisions in life and make our choices as best we can.
Another thought for you in respect of your two photos, is that I would suggest that as a woman society will give you more leeway with your appearance than it would as a man (at least in western countries)... As a man, society is likely to give you a hard time if you want to look like the second one on a regular basis... I know how you express yourself isn't your gender identity in your head and it's not about what you're wearing, etc, but it's something to think about.
Finally, whatever you do, don't forget to live life and have fun!
Hopefully I've been some sort of help – good luck!
Nb: it's also ok to change your mind – multiple times even!