i believe the clove needs to get a good frost in order to split to create bulbs
the general wisdom was plant on the shortest day (dec 22) harvest on the longest day (jun 21)
generally folk will plant it in oct'ish - while its still warm enough for the clove to get a bit of growth in and you will see shoots quite quickly (nice to have something growing in the garden at that time of year)
I've also put onion and shallot sets in around nov - they won't do anything but sit there until it starts to warm up again - i've seen shoots pop out in the last few weeks. so you can plant onion/shallot sets around the same time, but it's generally better to leave them until january - any sooner and they are just at risk of getting wet and rotting or getting pulled out by birds - who don't seem to eat them, just pull them out!!!
it is possible to grow garlic in spring, just that you might not get it to split into a bulb or it won't be very big.
I've heard of people planting whole garlic bulbs in spring and they just grow bigger - apparently this was an old victorian method of growing garlic - but most folk split them into cloves and get them in before xmas
but if it works for you the way you are doing it - why worry/change?
i love garlic, i planted 48 cloves in october, they have all come through nicely, but i'm now wishing i done more!! grrrr maybe i'll try planting some more just now!