Er...not really. Now instead of a having a length contrast in only two vowel phonemes, you have it in only one. Now it's your low level that's crowded: /æ/ /æː/ /ɑ/ /ɒ/.
I'll try to fix that. How would you recommend?
It depends what you're going for, really. Personally, I would either (a) extend the length contrast to more vowels or (b) eliminate it completely (unless of course I could come up with some really compelling reason for why it should have developed in only one vowel).
Does the phonology include the digraphs? If so, then I'll put those in.
Phonology includes everything
about the sounds of your language. Not just what the basic distinctions are but all the variants (positional, dialectal, social, etc.) and all the rules for combining then. At the very least, it should explain the syllable structure and any restrictions on clusters. (For instance, English may allow syllables of the form CCCVC, but that still doesn't mean that *tkven is a permissible word. It is in Georgian, however.)
I probably didn't go out of my way to make sounds that were (to me) different.
That's typical for a first go.
Anyways, if I do ever finish phonology, what should be next? I know words usually come fairly late, so conjugation? Declension? Cases? Tenses?
The order is up to you. Some conlangers start
with the words and figure out everything else from there. (This is particularly common when creating a "naming language", which may be used to generate names of people and places but no actual sentences.)
I guess it would help to know what your goal is with creating this language. To have fun, obviously, but do you want to be able to write poetry in it? Is it going to be the ancestor or cousin of another language you're creating? Is this an exercise to teach yourself something about a certain aspect of grammar, like how topic-comment languages work, or to pursue some thought-experiment, like what the language of a race of blind cave dwellers would be like?
There's no reason why you can't work on multiple aspects of Fragen at the same time, coming back revising bits after you've changed your mind about another component of the grammar.