There is a lady who started out as a box thrower, moved to management of a ramp, worked on her PPL, eventually took a leave of absence or quit to work for 2-3 years at a regional, and has been a pilot on the seniority list for around 20 years. The ramp she worked at, I forget where, didn't think she would make it, and were really surprised when she showed up at that same ramp in the right seat of a 727.
So, it can be done, but it is a multi-year commitment. Your FedEx experience should help you get an interview, I would think, but you will need to get the 1000 hours PIC, which means spending at least 2-3 years at a regional. Good news is, there is lots of movement, and lots of hiring across the industry, so this is a good time.
Good luck, and we are hoping you make it.
It will take a few years of paying your dues, but it will be worth it in the end, so keep your end goal in mind while you are working your butt off to get (back) here.