Astrology seems to be a bit flexible, so how do I know if I'm doing my chart accurately? I want to say I'm doing perfectly fine, but I'm new to this, and not quite good at seeing my errors. Am I being too overly critical of myself or is there really such thing as an inaccurate chart?

An inaccurately drawn chart you mean ? or inaccurate interpretations ?

Most software gets the chart correct - certainly any software you
pay for has a very good reputation of getting a chart correct.

Free software is generally good but there are some exceptions...
mostly due to atlas issues - like what time zone a particular city
keeping in illinois. The focus is usually time zone as the error
component.

Software that goes early - say earlier than 400 years ago can have variable
results with time zone and the year, month, day being interpreted
incorrectly.

But once you have the date, time and place - it is rare for a program
to be wrong as the ephemeris is common and well tested across
multiple vendors.

Astrodienst has a free chart drawing web based system that is
very reliable and I think there are some interpretations
available with their charts...

Generally, most professional astrologers have all the major
programs - if you post your chart details I can whip the chart
out quickly and post back :)

Does this help ?

so what have you got in virgo, as this sign is soooo detailed focused it can degenerate into nit picking. the only way to 'test yourself' is by doing readings with friends, family and on well respected forums