unfortunately, probably only your first 3 purchases counted.
No, the first three purchases from EACH RETAILER whose sales are used to calculate the official charts count. That means, if you used all 8 main retailers carrying the track (iTunes, Amazon, Tesco, Play, 7Digital, We7, HMV, TuneTribe) that were definitely known to be counted, you could in theory download up to 24 copies just for yourself.
On top of this you could 'gift' as many as 3 copies from any retailers who allowed this (iTunes and 7Digital definitely did, not sure of the others) and they counted as separate downloads as you only paid for them and others did the downloading.
Personally I only bought 11 copies (including gifting it), and kept some in reserve in case they were really needed for a concerted push at the end. For every track I've downloaded I donated 10 times it's price to Shelter... and current donations stand at over 80,000 quid and rising! Well done all involved :)