Personally after reading through this thread I think you're... mad...

But in a nice way.
Changing to a full frame or even top end APS-C body and selling your lenses and buying at least one full frame or good quality APS-C lens is going to cost quite a bit and I don't think it's something you can do on a limited or zero budget.
If you want to do landscape and macro and portraits you could possibly do all three with just one lens if you're not going down the cliché route of insisting on a wide angle for landscape and a long lens for portrait.
If desperate to spend money I really couldn't afford

I'd go for a shortish macro lens and accomplish all three of your wants with it. A 30 or 50mm macro will allow you to shoot pseudo macro flower shots, portraits and even landscape too.
None of these uses would require state of the art performance at higher ISO's, a fantastic cutting edge focus system, machine gun frame rates or a super wide aperture so I'd advise keeping your current camera.
So, my vote goes for investing in a nice used f2.8 macro between 30 and 60mm. If you're ok with manual focus you could even go down the legacy lens route and invest £10 in a AF confirm adapter and a get a couple of Zuiko primes such as a 28mm f2.8 (£20-30) and a 50mm f3.5 macro (£70-80) You could even add a 135mm f3.5 (£20-30) and if you spend wisely you'll have three very good primes that you can use with an AF confirmation adapter and you'll have spent under £150 and probably quite a bit less.