I am filing a patent for a software and I am using a patent service. They have given me 1 drawing for my process and I am concerned this may not be enough. It does describe my process but does 1 drawing mean that my patent may not be strongly defendable?
Disclaimer: the following is just personal opinion. Always talk to your attorney for professional legal advices.
You should read through all the claims and check if the specification & diagram substantiate the claims. If the specification and the claims only describe the preferred implementation but does not describe alternative approaches that are within the scope of your invention but are not obvious, then there is a risk a court may limit your claims to what are described (see O'Reilly v. Morse).
Details of various implementation need not be illustrated. If details or alternative approaches can be explained easily with just text, then you don't need diagrams. If you can't describe implementation using just text without confusing yourself, then it may be better to prepare more diagrams.
You need to be careful about what you describe or don't describe. If the draft doesn't substantiate the claims, then you try to add more explanatory text/diagrams after examination has commenced, you could be at risk of being considered "adding new matter".
On the other hand, describing too much is also not good. If later on you want to file a different patent, but your previous patent already disclosed key components, then your new patent application could be at risk.
What does your attorney say about this matter?