8 seasons instead of 4, why?

My Kepler Bb world has in total 8 seasons. 4 of those are transition phases. Their year begins on the first day of spring and their months with 9 day weeks are 65 days long. But that is just in Kepler terms. Their day is 2+2/9 earth days long. Now I made it so that in terms of months, each transition phase is 2 months long and the other seasons are 3 months long.

So here are their seasons in sequence through the year:

Spring: Most plants start growing on the first day of Spring, Cool to Warm weather, a lot of rain, a lot of sunlight

Sprummer: First transition phase, Weather starts to get hot towards the end, essentially their equivalent of our May

Summer: Hot weather, A lot of plant growth, dry spells for up to a week after a storm

Summer Fall: Weather starts to cool down and some tree leaves start changing color but very slowly here, essentially their equivalent of our September

Fall: Warm weather at the beginning, gradually getting cooler until it gets cold, a lot of color change, sometimes a sudden spike to summer temperatures for a few days to a week

Fallter: Cold weather, Last bit of color change, snow starts falling, December has been getting more and more like this ever since the El Nino started(During the La Nina just a few years before(2012 is a very good example) we had very hot summers, up to 100+ and pretty cold winters down to -4. During the El Nino though the winters have been getting warmer and the summers have been getting cooler(2014 is a good example of a cool summer, very few days did it get above the 80s)

Winter: Cold weather, no more growth or color change, lots of snow

Winter Spring: Cold to cool weather, some plants start growing in the snow, essentially their equivalent of March

You notice how I am naming these transition phases after the 2 seasons each one is between? But not only that but the season before it is what makes up the first part of the transition phase name.

Here is what I am talking about:

Spr

Summer

Fall

Winter

These are all the first part of a transition phase name and all except Sprummer have a first part that includes the whole spelling of the season before it.

The second part is named after the season that comes after the transition phase so that would be this list:

ummer

Fall

ter

Spring

Sprummer and Fallter both have an incomplete second part(ummer instead of summer and ter instead of winter)

But anyway, transition phases 2 months long are seasons in their own right but have characteristics more like that of the season that will come after. What could make it so that the year is divided into 8 seasons instead of 4? A wobbling of the axis can't explain it because even though this planet has 4 moons that all could potentially make the axis wobble, these moons are in resonance with each other and would at most wobble the axis by a fraction of a degree or some insignificant number. Too insignificant to be the cause of the transition phases. I mean if you have an earth-like axis, to go from spring to summer via axis alone would require the axial tilt to become negative. Moons can't do that, especially not for an earth-like planet.

So axial tilt can not be why there are 8 seasons instead of 4. Why else could there be 8 seasons, 4 of which are transition phases and thus shorter than the 4 major seasons?