Hi Pegasus,
This is going to be a long post, so I hope you'll stick with me here. I'd encourage you to do some additional research into bottom surgery before you make any decisions. It looks like you've gotten some incorrect information along the way, but hopefully I can help a bit with that.
Phalloplasty by the surgeons who are known for it involves microsurgery to reconnect the nerves in the phallus, resulting in a sensate penis. Sensation is regained over time with the majority of patients having both tactile and erotic sensation. The degree of sensation is largely determined by where the graft to build the phallus comes from, but the forearm graft is generally regarded as the best option for erotic sensation. I'm a part of a few different online groups for FTMs pursuing phalloplasty, and I have not seen anyone not have sensation unless they went to a surgeon that does not perform microsurgery. But if size truly does not matter to you then metoidioplasty may indeed be a better option, as there is (I believe) no risk to sensation.
For me, the most important thing is to be able to pee standing up. I do a lot of traveling via car and most of my hobbies are outdoorsy, and being able to pee standing up would improve my quality of life dramatically. This could be achieved with both procedures. I also want to aesthetically pass in a locker room setting. Again, this could be achieved with both procedures. As it currently exists, there are no erectile devices for phalloplasty that we can get in the US that I like. I've achieved enough downstairs growth that I'm comfortable starting with metoidioplasty. If I ultimately decide that I would like a more sizeable phallus, you can go from meta to phallo. I'm relatively young and insurance will most likely be covering my bottom surgery, so this is the best option for me. There are pros and cons to each procedure, but you really have to assess them in terms of what your needs are. In addition to metoidioplasty, I know based on my needs that I'll need to have a total hysterectomy, vaginectomy, urethral lengthening, scrotoplasty, and get testicular implants.
For most people who know they'll be pursuing bottom surgery, the first step is testosterone. Metoidioplasty cannot be done without it. I cannot think of a surgeon that will perform any kind of FTM SRS on someone who is not on testosterone. I'm not saying they don't exist, but I have not heard of them. For metoidioplasty, they require 1 year on testosterone to achieve enough growth to perform the surgery. Some give a range of 1-2 years, as this seems to be the time that downstairs growth maximizes. It can continue to grow post-op though, so not a big deal after the 1 year mark.
Most also require 1 year of real life experience, or documented time living as male. This could be from the time you start seeing a therapist, to when you start testosterone, to when you fully come out and update all of your documentation. SRS is a big deal and they want to make sure that you are completely content living life as male before you take the plunge. For guys with visible chests, that may mean getting top surgery somewhere along the way in order to pass as male and live comfortably.
You'll also need 2 mental health referrals saying that this is the next step in your transition. These would be written after you'd been on testosterone for the required amount of time, and typically after top surgery as well. The professionals writing them will need to document your transition and ensure that you meet the criteria for SRS that the surgeon follows. Most of them are using the WPATH Standards of Care.
Ultimately, my advice would be to focus on getting your top surgery while doing additional research into your options. There are additional ways to help maximize your downstairs growth if metoidioplasty is the procedure you're planning on getting, and those methods require some time and consistency.
