Want to check out a simple first sonnet to a gf?

The poem is certainly heartfelt. The format is correct, but the beats are off. If that doesn't matter to you, then the poem is fine. If you want to keep to pure iambic pentameter, you'll need to edit them. The slant rhymes you've used are very good, and soften the rhymes so they sound more natural...well done! Here is a suggested edit:

I've washed up on those sands unknown to man

Left prints I'll make again, should sea rescind

I've walked as light as sun on alpen spans

And left a hope that dwells amongst the winds

I've pressed past blizzard's blast to snowy peace

Kept fresh the thought I'd settle in snow yet

I've passed beneath the palm and fragrant tree

Kept fond the memory or brief Summer's breath

I've crossed the ever yawning stretch of sea

To find I'll never have my fill sky

I've chased down places that embolden me

To forge my links to life, and energize

Yet by this little pool, the Lotus blooms

And puts to rest my thirst for other rooms

Read the lines, and whether you keep them or not, listen to how they maintain the iambic beat across each line. When you do your own edit, keep this in mind.

Again, nice poem, I'm sure she'll love it.