Bottleneck at networking

Currently at a stage where I hit a bottleneck at networking for full time next year. I've already emailed every single alumni plus others with similar backgrounds that I can find online at multiple banks for multiple times, probably sent around 1500 emails at this stage from mid June to now, have tried all different strategies (longer version of background introduction, short version with CV attached), but nothing have seemed to work for me, and I've talked to around 20 people now and that's it. I can't see how else I can expand my network. There are several bulge brackets that have around 20-30 alumni from my school and I've emailed all of them multiple times but I've received zero response. There are also several people who finally offered to chat but simply stopped responding afterwards even though I follow up every week. I just feel really discouraged now, especially given that there are still banks I haven't talked to but can't find a chance no matter how hard I try. Is it because this is a tough year and not many banks are recruiting? What else can I do to expand my network?

Thanks - A very discouraged monkey