First I just wanted to say that reading your story I think you’ve been doing an amazing job so far. For someone with little formal education in computers you’ve accomplished a lot and learned a lot in a very short amount of time. I hope your employer and your colleagues understand how valuable of an employee you are. Being expected to port a legacy application to a new language and framework would be a big job for anyone, and it seems like you’ve been trying hard and making progress so far.
From reading your story, there seems to be two main problems. First, you’re being expected to learn a new language and related tools all your own, as well as port a new application to it. To tackle that issue, it might be a good to invest some time and effort in just learning C# and .NET first. If there is some leeway in when the project is due, it might be a good idea to sit down with a C# book, or an online course and get a feel for that first. Then you can apply what you’ve learned to your application.
Second, it seems like there is a general lack of communication in your company. It really should be management’s job to ensure that there is clear communication between all parties involved, but since it seems like that isn’t happening, you may need to stand up and take the lead. I really think you need to get comfortable with asking questions. That is an important skill for a computer professional at any level. If that is something that makes you uncomfortable, then definitely talk to your therapist about it. You could also try keeping a notebook of the problems you run into, and then ask one coworker one question each day to get more comfortable asking.
Finally, depending on the personalities of the other people in the group, maybe you can suggest having regular meetings? Even if you have a half-hour meeting every other day, that would give everyone a chance to get on the same page, ask each other questions and maybe even think through complicated problems together. Just to be clear, I understand that this might be a socially troublesome situation, but it’s also possible that your colleagues or superiors will be impressed with how you take initiative and give you the help you need.
Good luck, and take care!