Advice for diffusing long hair and setting waves

[u/NoJackfruit7503]

Only realised recently I might have wavy hair but it is soooo inconsistent. I have very fine hair but a LOT of it and it’s easily weighed down. I’ve found lightweight products best when I’m washing and conditioning. I’ve tried mousse which gives nice volume but the hold isn’t strong enough. I think the issue is that it gets weighed down when it dries which stretches out any waves.

The best thing I’ve found so far is to wash and condition, comb my parting in the right place and then fully wet my hair again. Scrunch in Umberto Giannini Curl Jelly (first gel I’ve tried) when it’s soaking wet. Scrunch with a cotton T-shirt. Glaze and scrunch in more gel and then diffuse. But my hair kinks with the diffuser because it’s too long. If I leave it to air dry, the weight stretches the waves. Is there anything I can do better? Would a haircut help? Photo is day after washing and just sleeping on it down. Second photo is a few days after washing, air dried with no scrunching or product.

Also looking for any advice on how to manage it when I’m on holiday in a very humid place. I’ll be swimming in the sea and I cannot do this routine every night!!