Has my nose collapsed? (Photos)

It is difficult to tell the significance of the changes as I do not have recent post-op photos for comparison.  But it appears you have some shifting that has happened since surgery.  I am glad you have a follow up scheduled with your surgeon for evaluation.

This is a difficult problem that can result from a reduction rhinoplasty procedure.  The mid- portion of your nose has settled and has a loss of support based on your photos.  You should absolutely visit with your original surgeon and also consider consulting with another surgeon who is comfortable with revision nasal surgery.  Good luck!

Your nose does indeed need a major revision procedure; few surgeons have experience in such interventions; to begin with I strongly recommend you seek varied and better opinions for your revision. Revisions in rhinoplasty are NOT touch ups or minor stuff dealt with, they are major overhauls even to correct minor aesthetic defects, keep this in mind.
Better photos are required, please provide perfectly aligned and well lit frontal, left and right lateral views, left and right oblique (diagonal) views, and underneath nostrils view, without them no grounded opinion is feasible; notwithstanding some clear conclusion can be drawn from your posted images, and indeed there are things to fix there:
-inverted V deformity: there is a collapse of the middle (soft) vault, caused by unproper / non effective / missing osteotomies which lead to dissociation betwen upper lateral cartilages and nasal bones; this is treated with the so called spacer or spreader grafts, an excellent solution to achieve two dorsal "rails" without disruptions or pinching; an of course with well done infracturing osteotomies
-open roof or broad bony dorsum (unclear from images): needing proper infracturing, maybe also some paramedial bone resection to narrow a bit the bones horizontally; also the osseous pyramid is broad, has to be narrowed; again well done osteotomies are the solution
-remaining hump: it is difficult to explain to me but seems very little attention was paid to shaving it; needs complete resection to leave it straight
-a possible supratip depresion: seems some hollowness exists at the dorsum above your tip; if this is confirmed some grafting is required
-typical pinched nose: due to preexistant anatomical peculiarities or maybe over resection of lateral cruras; batten grafts or total crura replacement are required
-unrefined tip: your tip does not fit you, oversized, too "fake", needs better work (likely it is "virgin" and was untouched, or alternatively a massive oversized grafting was inserted, unclear from images); treatment depends on the intraop findings: might be with tip plasties and plications or a Sheen's graft could be required-other irregularities: I guess on your right side there is a random heterotopic osteotomy, leaving irregularities; also some dorsal grafting may be required; considering your thin skinned dorsum you might need onlay temporalis fascia graft to camouflage the dorsum and leave a neat and compact look
-other touch ups: to be discussed, at nostrils, alae, custom designs requested by you, tip shape, style of nose, etc.
Difficulty of your procedure is very high, 8 out of 10 scale in revision rhinoplasties; surgical time 4-5 hours; do researh well about the real skills of your surgeon.

Feel free to request any additional information from me.