Thanks for the advise, I felt pressured as he held my head to is bum hole, while I was giving him oral, and held it there telling me to rim him, I felt like i had too by the tone of voice and slight force he was using against my head.
What can be really useful is practising what words to use when something happens that you're not comfortable with.
A simple "I'm not comfortable with this" does the trick in most circumstances, but it does take some practise before you'll be comfortable (ha) saying it.
"I don't offer [X]" is also a good phrase to practise.
Visualise yourself in the situation where you might be put in (i.e. his thrusting his bumhole into your face) and say out loud the phrase you will use.
I know it sounds like a load of hippy "believe in your positive self talk" crap but this really does help me.
Also don't have anywhere on your profile, or mention in person/on phone that you are new. Guys will really try to push boundaries as they think you won't feel confident to stop them.
If guys said "I haven't seen your profile before" I always just said "I've only just moved to this area" or "I've never advertised on X site before".