Your symptoms do not sound very benign to me, and given that plus your age at possible diagnosis, chances are that you may not experience a benign course. You describe quite a number of symptoms as well as new ones...sounds like an active disease profile to me.
The older DMD's have a fairly solid safety profile but with lesser efficacy. The newer DMD's that seem to show greater benefit in slowing progression, have much more serious possible risks associated with their use, although users are monitored far more carefully for those risks and the rate of risk is very low, especially in the first couple years of use. Still, these are risks that should be seriously weighed. There are a fair # of new meds under development as well, although they too seem to tinker with the immune system in one way or another. Since they don't know what causes MS, all it seems they can do is try to impact the immune response that is most certainly involved.
I wish I had begun DMD's earlier than I did because I developed a fair amount of disability before I agreed to take the DMD's. My neuro wasn't that keen on me taking them either, so it was easy to put them off. Unfortunately, a lot of damage was done during that time and I have a lot of lesions and a lot of neurological symptoms that impact my daily life. I am somewhat risk-averse and I am not much for being a guinea pig when it comes to treatments. The prospect of developing PML from treatment, albeit a small risk, is terrifying to me as that to me is worse than MS. Many others are willing to take that very small risk because of the clear benefits of treatment born out by research. The risk is also very very very small the first couple years of treatment.
I really think it all boils down to weighing risks of disease progression against possible risks of treatment. Some doctors are more conservative than others, and you can find a doctor on any side of this issue of 'when to treat'. We all too have different levels of acceptable risks, it is a very personal decision. It is important for you to have a realistic understanding of how MS progresses, and what exactly are the risks from the meds. In terms of % of people developing the serious side effects, it is very low, although of course if you are one of the unfortunate people who develops those side effects, it won't matter to you that most others do not. You have to be comfortable with the risks you are taking and feel they are worth it for the benefits of slowing the disease progression.
I wish you good luck with your decision. The nice thing about taking these meds is that you can decide to stop treatment at any point as well (although with some of the newer ones like Tysabri, you may be at risk of a rebound disease effect if you stop too quickly after starting). I suggest you make a list of pro's and con's both for and against treatment. Read the studies to learn the benefits of each treatment as well as the risks, realistically. Read the natural history studies to inform you of what generally happens without any treatment. Tens of thousands of MSer's are taking any one of these treatments and are attempting to impact the course of their disease. Regardless of what you decide, you won't be alone in that decision.