Screw and batten thickness... will my shelves fall down?!

Hello - would appreciate any comments on my plans for my sitting room alcove book shelves...

The alcove is 100cm wide. Walls are plastered brick.

I am going to use 18mm MDF for the tops, fixed on to battens on the side walls and along the rear wall. 6mm MDF underneath and front to create a "box look".

Now, the wood I have for the wall battens is 18 x 28mm. The screws and plugs to attach these to the wall are all-in-one 6x60mm hammer fixings.

In the past I've used 2x1 for shelf supports, but with these shelves, I would like to create a sleeker profile hence the use of 18x28. Is it suitable? Are the screws long enough?

For many years I have lived in perpetual fear of my handiwork collapsing - advice from the experts on this one would help me sleep better!

Cheers

Personally, I think they are a just a little short. I always like to have at least 50mm/2" of a fixing in the wall.
Also, with such narrow battens, there is a risk of splitting them with hammer fixings. I would use at least 65mm/2½" (preferably 75mm) No.8 countersunk screws through pre-drilled holes in the battens with brown wall plugs.

Thanks for that.

If i use standard rawl plugs and the longer screws as you suggest, could i still get awau with using the 18x28 battens?

Thanks!

As advised, pilot drill and countersink the battens first, and they'll not split.
John