Superday Stories

I have made it to a lot of final round interview but never seem to convert them to an offer over the past 1.5 years since I entered investment banking. Initially, I figured that the banks wanted an associate with some deal experience. But now that I have closed a few deals and then not able to convert a final round interview I feel I'm not good enough! It is kind of messed up and it gets to you.

Quick Background:
1. International Candidate working in the US (no sponsorship required/Green Card)
2. Undergrad - Engineering
3. Work Ex - Big 4 (3.5 years)
4. Grad School - Non-Target Business School (MBA) University ranking - top 15 in the world
5. Post Grad work Ex - Boutique IB (class of 2017 / 1.5 yrs exp.)

Made it to final round / superday for the following banks:
1. Baird (hadn't closed any deal prior to the interview)
2. Jefferies (hadn't closed any deal prior to the interview)
3. Stifel (hadn't closed any deal prior to the interview)
4. Stephens (hadn't closed any deal prior to the interview)
5. Piper Jaffray (closed 4 deals prior to the interview)
6. Cain Brothers (closed 1 deal prior to the interview)
7. Other Banks - JMP, FMI etc.

Courses I have done:
1. Wall Street Prep - Accounting Course and Three Statement Model
2. Breaking into Wall Street - PowerPoint Course
3. Breaking into Wall Street - The PDF with 300 technical questions
4. Rosenburg - Technical questions

I feel like my technical part of the interview must have hurt me. Most of the interviews are from the "breaking into wall street - 300 technical questions for IB interviews" and I think I get most of them correct. So I'm not sure if its the technical that is holding me back or that there are other candidates that are better than me, or my non-core school title, or something else. Some interviews had a superday others only invited me and continued the search process after turning me down. I don't know what am I doing wrong but I plan to stop focusing on interviews now and just join a community college after work and take basic accounting classes. I need your insights on the following:

1. What the hell am I doing wrong?
2. Are my technicals just too poor? How do I gauge it?
3. Should I keep taking interviews with other banks? I fear that I'll exhaust the list of banks in the market and then no one will want to hire me (as they have interviewed me before and would have their notes on me).

Appendix:
1. I have tried asking for feedback but almost always never get one.
2. I get interviews through both head hunters and directly applying online.
3. I have good modeling skills and ppt skills (I've recently created a resume package with a deal sheet and a redacted CIP).
4. I am a hardcore networker and have landed with all my internships and jobs by reaching out to people on LinkedIn.
5. I am comfortable asking the PE group that I recently closed a deal with to provide a reference for me (I also saved an appreciation letter from the CEO for the company we sold recently).