Spelling with Double Consonants

ima priddy gud spellar moste ove th timm.

But for some reason, certain words with double consonants, especially two sets of double consonants, trip me up: Renaissance, harassment, embarrassing, millennium, parallel, Mediterranean, misspelled.

R e n a i s s a n c e - Renaissance Renaissance Renaissance
h a r a s s m e n t - harassment harassment harassment
e m b a r r a s s i n g - embarrassing embarrassing embarrassing
m i l l e n n i u m - millennium millennium millennium
p a r a l l e l - parallel parallel parallel
M e d i t e r r a n e a n - Mediterranean Mediterranean Mediterranean
m i s s p e l l e d - misspelled misspelled misspelled
What's funky--what trips me up--is that, even though I know these words have double consonants, sometimes in the moment of writing them, I freeze up and can't remember which consonant is (FOOLISHLY!) there twice. It's just bugging me because I have to look up 'renaissance' titles a bunch  and keep mis-typing it and getting the wrong or no result in my search as a result. thought I'd stop and practice my double consonant words so I wouldn't have to constantly face this problem!

UPDATE: der, forgot one of the most prominent ones considering the spring weather
p e r e n n i a l - perennial perennial perennial