Check whether the form helps in practice.
Before launch, try the form on a phone using sample details, including an uncertain budget or date. Check that a failed submission preserves the answers and that a successful submission reaches the agreed destination.
After launch, review genuine enquiries separately from spam and internal tests. Record which answers helped you decide the next step and which questions still needed a callback. Compare completed enquiries as well as missing details: more filled fields are not an improvement if useful customers stop submitting. With low traffic, keep observing rather than claiming a conversion uplift from a few visits.
The GOV.UK question-page guidance supports asking only for information you need and clearly identifying optional questions. The examples above apply that principle to service enquiries.