How is your memory load? My guess is you've reached the part where your SSD-speed (both reads and writes) is the limiting factor due to the low RAM. There's a huge difference between SSDs: some have very bad performance when it comes to combined reads and writes. If it's a budget SSD, that may be the cause.

But, on a similar setup, it took me less than 2 days to complete the IBD. See this post on my progress.

Considering the low price of RAM, if at all possible, add some That should make things run much smoother.