well, apparently, something's changed. so it's up to us to find out what it is.
I'm assuming from your statements, bushy, that in the 18 months you've been riding this bike, you haven't made any changes to your suspension or chassis (ride height). Stop me if I'm wrong. I'm also assuming that up until recently, you haven't had any of the aforementioned problems, correct?
Before you start looking at mechanical troubles, is there any possibility that either:
a) your riding has progressed, causing you to be unsatisfied with what was previously a satisfactory setup?
b) your riding style has significantly changed?
c) your weight has significantly changed?
If you feel that one or more of the above apply, then it's still something that can probably be addressed with suspension adjustments or changes.
If not - then yes - it's possible in 18 months for suspension components to go bad. could be acute damage in either the forks or shock, or just time for a rebuild/recharge/new oil.
Post back & give us some more info. it's sometimes complicated getting to the heart of the matter dealing with suspension.
Also - it would ideally be best to get you setup with springs for your weight, and probably change the fork oil level, and get the bike sagged (yada yada yada) - but I'd like to see why what was working for you before is no longer working for you now first.
BTW - simple answers are rarely the right ones. Some advice you get won't only not help... it could be 'Dangeruss'