To the OP: You definitely had some challenges, and for a new diver, it can be scary when things so wrong. Scuba diving, by nature, provides new learning experiences all the time because nothing in the ocean stays the same and each dive, even in the same location, can be different. All the previous tips are great. I'll throw in my two cents here. I don't get seasick, but I take a lot of seasickness aids with me for the just-in-case occasion and I usually end up giving some away to others. I like ginger chews (not hard candy) made by The Ginger People,
Gin Gins - US The Ginger People. They are widely available. I get mine at Whole Foods. With the chews, you can nibble on them a bite at a time Whatever you buy, read the label for the highest percentage of ginger--10% or higher. Some products only have 5% and it's not as effective. Then there's Meclizine, which is the active ingredient in name brand anti-nausea meds and it's a 25 mg pill dose. You can buy meclizine anywhere.
As referenced by others, you can also try the scopolamine patch that goes behind the ear. I used this for the first time a couple of months ago as a preventive for an 18-hour ocean crossing with rough seas on a liveaboard. You take it 12-24 hours before getting on the boat and it lasts for about 3 days. However, there are side effects, so check with your doctor and pharmacist. The side effect for me was extremely dry mouth, and I mean so dry that I was hoarse and no amount of liquid, gum, mints could bring back my saliva. I took it off at the end of the second day.
Only in the last couple of years have I taken the stress off myself to do every dive offered. There are times when your gut, instinct, intuition, whatever you want to call it, gives you pause to assess whether a dive should be called. On a recent liveaboard, dive number 1 of the day was totally screwed up for me by another diver, which caused me to miss the dive briefing. My stress was high, I lost my zen, I got a quick rundown of the briefing from the guide, then hurried to gear up. I was completely geared up and walked to the edge of the boat to get into the panga, paused, mentally reassessed, turned around, and went back to my seat and took off my gear. Being frazzled from this other diver's actions, I was not in the right frame of mind, so I aborted the dive. That was the right decision for me in the moment.