@Joinmelb
Clinical trials are a lot of work for all concerned--lives and careers hang in the balance.
I think you should hang in there for as long as possible, but I also think you should talk to the trial coordinator, or the contact person assigned to you, about your concerns. Really talk to them.
There is always an expectation that there will be some 'attrition' over the length of the trial, but I'm betting they won't want to lose you and the data you represent. There can be too much focus on the career side of these things, but there would also have been an undertaking on their behalf to look after your general wellbeing. Negotiate with them.
In order for research to be credible there has to be consistency in the process, but that doesn't mean it's all a one way street. There has to be some flexibility because humans are not machines. Grueling treatment and monitoring schedules are tough enough without having to manage a complex family life at the same time.
If this works it could be life changing for you and others who will find themselves in a similar situation in the future. Thing is, they are called trials for a reason, there are so many unknowns. Those unexpected findings, positive and negative, need to be acknowledged and built into any conclusions, so it's really important to give all the feedback you can during the process. Good on you for getting involved in the first place. MXX