That sounds normal for a vm. You don't typically worry unless available entropy drops below that 100-200 average. The key measure is the sequences that come out of that entropy.
You should use the
ent program to test your random sequences. You worry when you start seeing tests fail here.
This site has a good process for testing randomness.
We can collect random data from /dev/random using "dd". This command will collect 8,192 blocks from /dev/random and output the results to the text file we will call "random_output". NOTE: if your /dev/random generator is too slow this command will take forever to finish. The random_output file should be around 1 to 4 megabytes in size depending on how large a chuck is on your system. For now, if the dd command does not finish in 3 seconds or so hit Ctrl-c to kill dd.
dd if=/dev/random of=random_output count=8192
Then, after you've built your ent program:
Analyzing the results is a little beyond the scope of your question, but what I linked can fill in the ancillary details.