You might have more success if you explain your business model a bit better. What pain point are you addressing? Who's the customer? How big is the market? How do you plan to introduce your innovation and induce behavior change in the current marketplace and insert yourself into the transaction? etc..

I am not doing a startup, so take all these suggestions fwiw.

1. You website looks great. Looks like functionality is not fully done though? I was clicking on "Book Now" but it didnt do anything. Maybe it was because I did not sign in. Maybe make that clear in error box.

2. YC keeps repeating the advice to do things that do not scale; focus on week at a time. Your vision is ambitious-- which is great, but on execution, scale down to bare minimum. e.g.,

2a) Website is designed for search anywhere, but drop down is only for Phoenix. It is totally fine to focus on Phoenix only initially. In fact, go more aggressive, remove that screen altogether, make it clear that this is only for Phoenix. In fact remove the search form too. Directly list the 8 results you have on the page.

2b) The result page has airbnb like feeling.. but you have only 8 listing so far. Can you make that result page more catchy, remove the need to click through into each listing. Design it more like Pinterest, large picture, title, brief description, and book now link, all in that page. No need to click through to detail page. FWIW, airbnb in its early days went to each one of their hosts home, took pictures, and edited descriptions manually. Totally worth it.

2c) Why ask for account? You need that only for repeat users.. for one time bookings, just give them a form with email/phone, etc. fields. An account is a high barrier for intial adoption. Dont force it until you must. PG hated even a service like quora for a long time, because it forced an account creation.

3) Who is your target user? Initially, you do not need internet to promote this type of service. Do something old-school, like physical banners, with a phone number. People will call you, and you tell them on phone which doctors are available for what price. And do the booking on phone. Put your fliers in walgreens/cvs (dont worry about policy, you only need to convince the store manager). Put flier infront of walmart or wholefoods or target-- depending on demographic of your intial users.

4) Dont beat yourself for not getting into YC. They have two goals-- a) do good in the world, and b) make money. I can see you are early enough that signal is not clear for making money aspect. Fix that-- show some intial traction by doing things that do not scale.

5) Their feedback email tells you clearly that the issue is founders have varying commitments. Fix that. You do not need four founders-- two great ones, who are on board full time or with significant commitment in time or money-- is sufficient. Talk with them, ask them to leave if they are not on board fully. It is even fine to do this alone-- you are passionate enough, and you will have no excuse then.

6) If you need help with programming, I can offer some of my free time. Tweet me: @kabragovind