daffodils

this is my first time with daffodils- they haven't bloomed yet, for one thing. and they are extremely leggy to the point that they flop over. why does this happen? not enough water? too much sun/heat?

Have you fertilized them a lot? I don't grow bulbs, but I know with other plants they can get floppy/leggy either from not enough light or from too much nitrogen fertilizer, and since yours haven't bloomed yet that could definitely be the case, lots of nitrogen will make lots of green growth but no blooms. There are fertilizers special for bulbs that I think have a higher level of phosphorus which encourages blooms.

what kind of daffs are you growing or color of them so i know what you have? that way i can know better what to tell you it maybe and what kind of location are they in? like full sun shade part sun ect. i don't ever fertilize my daffs mother nature takes care of them on their own they should be carefee you shoudn't need to use it. also it depends on if you got them from a store and if they were potted and force grown or if you started them as bulbs on your own. there is actually a few things it maybe or just the kind it is.
silkie

I think they are ordinary yellow ones, adn some paperwhites, but I don't know. They were in part sun, never fertilized, not watered often but the soil is clayey so its moist

Paperwhites are known to get very tall and need staking. I just forced some over the winter, and everything I have read about them says they have a tendency to flop over. Try staking....also, daffodils are closely related to paperwhites...so maybe this is why they're flopping over too?

Some daffodils do better in warm climates than others, too. Look for tazettas and jonquils in the daff catalogs. If you love 'em all, look at White Flower Farm's collection of daffs for the South. It's a box of 100 bulbs at a decent price, at least 10 different kinds but not labeled. You might not want to get anything else from WFF (see the Garden Watchdog!) but their bulbs seem to still be just fine.

Daf's as we call them in Scotland need rich, well manured soil,dug in the season before planting your bulbs, protected by LIGHT shade, under trees or hedges, or a spot that gets later sun.
You say that you are gardening on clay soil, this needs to be well broken up with perhaps sand or the likes added to help stop the bulbs sitting in wet to damp earth,it also has less air in it, over time, the bulbs just rot, then if the temp rises too quick, this causes less flowers or even none, the following year.
Daff's should be planted about three time the depth of your bulbs size, so if you have a 2 inch bulb, it needs at least 6 inches or deeper, I am not pro, however, I was tought that a bulb is like the food larder for the plant, therefore I dont feed mine till after they have finnished flowering, then as the green leaves start to die down, feed the so that the bulb stores the goodness for the next years growth
Dont cut off the green leaves as this is food for the bulb, as it dies down the bulb takes in the goodness from the leaves, best time to tidy the daff's is once the greenery turns yellow, it is then easy to just pull away without harming the bulb, did you get your bulbs for a reputable place ????? I would be inclined to lift some of your bulbs after the leaves start to die down, that way you can find them, dry them of in the sun or warm place, then tidy up the bulbs even take the roots off, and plant them in a large pot with good soil, if they flower better in the pot next spring, then you have a soil problem in your garden if they dont flower in the pot, then question your supplier, it could be the bulbs just are not mature enough yet, dont throw them out incase they just need a better position.
Sometimes if the bulbs are not deep enough in the soil you don't get flowers, that is what we call growing blind. hope this is some help to you, I have had a whole banking mixed with shrubs, covered in Daff's, been in the growned 15 years now, it is stunning so good luck.