The best way to approach love spells is to cast a spell upon yourself to make you the kind of person they would fall in love with, or to make yourself irresistible to them. Since you've probably already tried the former, using magic to bring you whatever that special attractive something is might be a good idea. If you wanted your spell to have a high level of free will, you would use wording like "I call power unto myself to be (whatever it is you want) …" in the beginning of your spell. You might want to do this part in a pre-ritual cleansing or something. You could take a bath, drink the chamomile tea, and make a sachet with the vanilla, cacao, rose petals, peach, and a bit of oil. These reagents draw love and lovely qualities to you. The other ingredients, ginger, sage, lemon, and cayenne are all more firey, good for the strength of your spell, the powerful love and intimacy you want, etcetera. You might want to save those herbs to use in actually casting your spell.
When I use herbs in spells I usually either mix them into my chalice full of hot water and inhale the aromas, or light a charcoal disc and drop them directly onto the coal like loose incense and scry in the smoke for omens. You could do this while saying the words to your spell. Using a gum or resin like frankincense or copal ground up into your other herbs will give your loose incense a nice sparkle when it combusts, great for magical "spikes" while reciting a spell. If you have the luxury of an outdoor fire pit or something, throwing loose incense is great, and you could throw the spell into it as well. If not, burning the spell in candles would do well also. You wouldn't want to rub the mixture on the paper and try to burn it, it would burn irregularly and interrupt your concentration.
Your wording is good, but a specific time limit does infringe upon free will. Your aim should be to attract the person, have your full potential and good qualities revealed to them, and for it to be determined whether or not you're meant to be. The only re-wording I would suggest is
"I give you the power to reason/now and again when we witness this season"
This could open up the potential for the person to "snap out" of the spell at the same point in the year after your first year of happiness. If that makes sense. Like, if everything is going well but there's really something being suppressed by the spell, it wouldn't hold influence over him much longer.
So I would do it like….
-Ritual cleansing bath with vanilla, cacao, rose petals, and peach for attractiveness and pure intentions
-Grounding, clearing, casting circle
-Making of incense (this could be done before too) lemon, ginger, sage cayenne
-Charge and light candles, maybe carve runes or anoint with oil
-Burn or inhale incense vapor, visualize or interpret smoke omens
-Once visualization is at a good peak, recite the spell, if burning incense, use a lot now
-Visualize again, now begin to earth the power, perhaps scry for omens in the smoke, open your circle and release the energy out to your love!
Hope this isn't totally different from your regular practice or too much! It just seemed like a fun question to answer