There is no hard and fast, birght-line rule as to what constitutes a material change in circumstances warranting modification.
If all or most of the circumstances that you have described in your question are new (i.e., did not already exist and/or where not anticipated/foreseeable at the time that current custody order was entered), then it sounds like you have a very reasonable argument to make that circumstances have changed in some material ways since the custody order was entered. Whether that will result in you gaining primary custody or not depends upon whether you can show/persuade the court that this change "warrants" modification and that giving you primary custody is in the best interests of the child.
The requirement to sufficiently allege a material change of circumstance is primarily to prevent a parent who is not happy with the outcome of their custody case from returning to court over and over again in an attempt to relitigate the same old issues or facts and/or to make an end-run around the time requirements for properly appealing a custody decision. The changes that you mention in your question are substantive, not trivial. Once you present the facts at trial to support that these alleged changes have occurred, your primary focus will need to be on showing that the factors listed in Section 20-124.3 of the Va. Code support a finding that it is in the child's best interest for you to be primary custodian.
You will need to prove your case by providing admissible evidence (including documents and witnesses) to the court to substantiate your position. This may include the school counselor, CPS reports (which, in and of themselves, are not going to just be accepted into evidence), possibly his employer (if he disputes your assertions about his work schedule), etc. Accordingly, it would be extremely helpful for you to have an attorney represent you in your case (the attorney should know the rules of evidence and how to conduct aggressive pre-trial discovery, as well as securing the witnesses, getting around non-discloure issues, requesting an IPE if necessary, requesting a GAL be appointed, etc.).
This response does not create an attorney-client relationship and is intended for general information purposes only.
Ms. Mandell does a nice job of describing what you need to consider. I will only add that before you file -and I hope you will get an attorney to assist you - start a cookbook. For each point you raise write out every thing you has that will support that issue (eg. cigarette burns - witnesses, cps report/ worker; graduation - diploma; job - letter and possibly employer/ supervisor). Have filled in to better assist your attorney.