Another onion question....sorry!

Hi all, I planted some sets last autumn, they all have healthy leaf growth & out of curiosity I took one out at the weekend.

The original "set" has gone & all that remains is a plant about the size & form of a small spring onion, there is no bulb as such & nothing except greenery showing above the soil.
The original sets were planted with about 1/2" showing above the soil level.
Did I plant too deep or is this normal.
I planted some more sets at the weekend just in case 

I also have plenty of seed gathered from last year, is now a good time to plant in an unheated greenhouse.

Thanks.