Also note that by itself tip opening is not so relevant, the response and resistance you feel depends on facing length, type of facing curve along with the tip measurement.
I agree with this comment.
I would suggest a " middle ground" mouthpiece, with a medium ish lay.
if you are thinking the.90 is too much, try 5 or 6 ish. .70/75 ish
as you already have Vandoren on tenor, perhaps try that brand.
I dont like the Java mouthpieces on alto, but lots of folks do.
I do like the V16 range. I have a 5m and a 6s. the 5 is great and still has lots of power. think phil woods, cannonball vibe. The 6s is louder, more free blowing , but still with a nice core.
also think abou a meyer 6 medium or small chamber. similar vibe to v16.
these vandorens and meyers are very flexible and can be made to work in all situations.
keep an eye on Ebay. vandorens and meyers always pop up. buying 2nd hand means you can pretty much try things and not lose much/anything if it isnt for you. Its a bit risky financially, buying new without trying, as they are such a personal thing.
if you do want metal with a bit more bite built in. i do have two metal yanagisawas for alto. a 6 and a 7, that I will sell, with the relevant donation to the cafe. But these arent a match for everyone !!