Campsis need A LOT of heat in order to flower and even then they often don't until they are a decent size. The only time I've been able to get satisfactory flowers on a Campsis (and that was a Mme Galen too) was growing against a south-facing red-brick wall in central London.

That one tended not to start flowering until really late in Summer - August if I recall - and then carried on until frosts in Autumn. It's that long, hot early summer build-up that they need to stimulate the production of flower buds and this summer (like the previous two) has been less than ideal in that regard.