What are the chances of catching an STD during unprotected?

[Pixie]

Yes of course you can catch STI's whilst still using condoms.

You can catch things like:
HPV (genital warts) which approximatelya 3rd of sexually active people already have in the UK.
Herpes (can show no signs and then all of the sudden one day when your run down nasty blisters can form on your cock. Or of course you could be a carrier. Also, this virus stays with you for life)
Scabies
Genital lice (crabs)

Condoms don't make it impossible for HIV and other STD's to be caught but significantly reduces the risks.

This is the reason why you should get yourself checked out regularly even if you use condoms. Also, it can take up to 2 weeks for these diseases and infections to show up in tests. So you may need to have follow up check ups done to be safe.

Waiting until symptoms show until you GOTO the clinic is a very bad idea. Not only will you be passing on these STI's to others if you have them, but even the ones that you seem to think are not very dangerous, are in fact very dangerous.

For example, chlamidia. It shows no signs and you can have it for years until one day you get very I'll. By this time the virus will have already done permanent damage such as infertility and reactive arthritis.

I think it may be an idea for you to go to the clinic to not only get tested but also to get information on the risks from the nurse.