Congrats, @JustPickleRick that's an amazing loss!
@Chopsy123 and others, yes: the leftover after the 4th dose is the 'golden' dose and it is more than a usual dose. I wouldn't buy syringes on Amazon, personally, I ordered from here: https://ukmedi.co.uk/products/fms-micro-syringe-32g-8mm-1ml-fms-fms-32g-10ml-ukmedi-co-uk and bought alcohol wipes too, it cost me around £15 delivered and they were very efficient. I figured if I only use this dose once a month, £15 for a year was very reasonable! It was super easy as you can draw out and inject without changing the needle with these. They were recommended on the other MJ threads here. I considered using a bit more than 2.5mg (0.6ml) but decided not to in the end, as 2.5mg is still working fine so I didn't want to rock the boat. I drew out as much as possible, then 'primed' by pushing the excess back out. Also - 1lb off is better than 1lb on! You're doing great. 
@SnowWhiteisMyFavourite - great loss for you too, well done!
I weighed this morning and I've lost 3.5lb this week. Very pleased with that as evens out the 1.5lb I was a bit disappointed with last week. My period is just coming to an end today though, so I'm thinking that might explain the sluggish pace before?
So, SW: 19st 1lb 
CW: 17st 13lb
GW: 11st 7lb (for now, we'll see how I feel about that once I get there).
Current total loss: 16lb in 4 weeks. Not to be sniffed at!
I swam 750m this week, and did 30 mins of pilates last night, which hurts now! Hoping to do 1.5km of swimming (over 2 sessions) next week, so we'll see how it goes. I've been utterly shattered this week. Not sure if its MJ related or not, but my sleep has been very disturbed and I've found being so tired affected my mood. Having a relaxed weekend though, so hopefully it'll give me time to reset before work again next week.
Hope you all have a lovely weekend!