As far as I am aware, the E106 will cover you in Spain for up to two and half years only if you have paid NI in UK for the 3 years prior to your move. The DWP website explains it:
Healthcare provided under the E106
If you move to an EEA country to live but not work and don't receive a UK benefit, you may be eligible for up to two-and-a-half years of state healthcare, paid for by the UK.
You will need to apply for an E106 with the the Overseas Healthcare Team (Newcastle) and prove that you have worked in the UK and paid National Insurance contributions up to three years before your departure.
For further advice, contact the Overseas Healthcare Team (Newcastle)
Overseas Healthcare Team (Newcastle)
Room TC001
Tyneview Park
Whitley Road
Newcastle upon Tyne
NE98 1BA
Tel: 0191 218 1999 (Monday to Friday 8am-5pm)
The E106 will entitle you to treatment on the same basis as a resident of the country you moving to. This may mean that you have to make a patient contribution to the cost of your care.
When the cover on the E106 expires, you cannot get any further medical cover from the UK until you are in receipt of a UK state pension. It is up to the country’s authorities to decided whether you are eligible to join their healthcare scheme.
You will also be entitled to a UK-issued EHIC, allowing you to visit other EEA countries besides the one your are a resident with.
The fact you haven't paid NI for over 3 years will not give you any cover in another country.
Looks like you will have to keep "bending the rules" as so many do. Unfortunately, this situation now applies to other regions of Spain, particularly the Valencia region which has now moved the goalposts.