I agree with RomanJames: could be BP and a personality to match (BPD). The "impulsive" thinking would be obsessions. That they are rather about endangering oneself and others could also be due to a personality near the "psychotic spectrum" borderline (BPD). It would rather depend on the person you "try" to endanger: are you close? If so, BPD is not an unlikely causative factor (it could still partly be caused by other anxiety/neurotic (cf. psychotic) issues). If not (only), it could be a more classic form of neuroticism. A personality near the borderline (i.e. borderline personality disorder; BPD) can cause such obsessive thoughts but an anxiety disorder alone can do the same. What's more, very many people have such obsessions in a mild, "background" form. Only if they take centre stage or you add compulsions (you actually do endanger people or you do something else harmful as a result of your obsessions) is it something to treat. Otherwise, it is just something to analyse to see whether it is (only and) "typically" a borderline personality trait or not.

I use this phraseology about BPD, which is rather uncommon, but certainly not incorrect, to talk about borderline, to put it into perspective: how it relates to psychotic disorders.

It is a personality one develops and that literally borders on psychotic behaviour.

Now, there could be two reasons for this: you have real psychotic (e.g. BP, but schizophrenia is also very well possible) vulnerabilities/tendencies. A personality that is very much like BP, in that case, helps to deal with the underlying psychotic problems (not in the best of ways, but at least it does). High expression and confusion about emotions (especially in relation to others) is common. Seeing criticism as a total nullification/denial of oneself is common. Sabotaging relationships (as self-protection and to give a "valid" reason for emotional turmoil) and oneself (e.g. one's health) is common. Reactive, short mood changes are common. Impulsivity is likely.

Personally I suspect it could be very well that BP and BPD coincide.

However, a borderline divides two areas/categories. On the other side one (likely) first finds unipolar depression. The borderline personality in this case is also used to give expression to (internal) emotional turmoil and confusion. However, other more psychotic tendencies don't need this relatively regulated/controlled release. There (probably in general) tends to be less impulsivity. Finding reasons for feeling depressed, however, may still cause self-sabotaging behaviour and strong emotional reactivity might still occur, but tends to cause depression more so than strong feelings of happiness, joy and elation and impulsivity: unipolar versus bipolar disorder lite.

I would say BPD is more likely than BP, but BPD and BP are more likely than BPD and depression only. Schizophrenia, another possibility (but relatively unlikely) is very unlikely, I think (or you must be leaving stuff out).

Good luck at the doctor's. I would wait till the 1st of April. If it is BP, get used to waiting a lot longer, probably. Average time to get the proper treatment is about 10 years. Take your time to really analyse your problems, keeping an open mind, but hopefully this helps a bit.

Edit:
NHS and all, I'd say it's rather 30 years. Just kidding...

But do come prepared: history of problems, any energy and activity changes throughout your life: periods of sleepless nights or "obsessive" goal-directed activity, not doing as one is told leading to serious problems or missed chances, regretting it later during periods of depression. Feeling guilty for being different and blowing things, but not always. Feelings of being out of control.

Really losing control (so not just buying stuff, but buying stuff despite you realising (maybe told numerous times) it is really gonna cause problems (but you will earn so much money later that it's all fine and carefully planned, you might think)) distinguishes between a problematic, borderline, personality and BP. Nothing can go wrong! It's all under control! Try and stop me, I dare you! (fond memories... Really. But I am always a bit crazy. Do find a way to keep it under control, but never feel guilty for it: never feel guilty for who you are).